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13+ Best Reverse Osmosis Systems of 2020

best reverse osmosis system reviews

Table of Contents

What Is A Reverse Osmosis Water System?

Reverse osmosis is a popular water filtration solution that can provide high-quality, safe and great-tasting drinking water. It works by using pressure to push water through a partially permeable membrane, removing impurities and making it cleaner and more desirable for drinking.

There are a number of water filtration methods available, but reverse osmosis has proven to be one of the simplest and most effective for the average home or business owner.

There are a number of cost and performance-related benefits to reverse osmosis water filtration. In many cases, this form of treatment offers cleaner water with far fewer impurities when compared to alternative filtration methods.

Water that’s been treated by reverse osmosis filtration is far better for you than water that’s been left in its unfiltered form. Because reverse osmosis removes impurities from water, including harmful chemicals, molecules and particles, drinking reverse osmosis filtered water will reduce your risk of disease and illness.

Best Reverse Osmosis Water Systems

  • Waterdrop RO
  • iSpring RCC1UP-AK 100GPD
  • Home Master TMHP HydroPerfection
  • APEC RO-90 Ultimate Series
  • Express Water Alkaline Reverse Osmosis Filtration System
  • Global Water RO-505
  • Greatwell 400 GPD
  • NU Aqua Platinum Series
  • Olympia Water Systems OROS-50
  • Whirlpool WHER25
  • Brondell Circle Reverse Osmosis System
  • AquaTru Countertop Water Filtration System

Futher Information

Waterdrop RO
Waterdrop RO Reverse Osmosis Water Filtration System
Filtration: 7 stages
Type: Tankless
Water Production (GPD): 400
Dimensions: 18.1 x 5.7 x 17.8 inches
Weight: 31 pounds

👉 Read the full review
APEC ESSENCE ROES-PH75 Reverse Osmosis Water Filtration System
Filtration: 6 stages
Type: Alkaline mineral pH+
Water Production (GPD): 75
Dimensions: 16 x 5.2 x 17.5 inches
Weight: 25 pounds

👉 Read the full review
iSpring RCC1UP-AK 100GPD
iSpring RCC1UP-AK 100GPD High Capacity, Boosted Performance Under Sink 7-Stage Reverse Osmosis Drinking Water Filtration System
Filtration: 7 stages
Type: Remineralizing, UV
Water Production (GPD): 100
Dimensions: 15.3 x 9.1 x 18.1 inches
Weight: 35.3 pounds

👉 Read the full review
Home Master TMHP HydroPerfection
Home Master TMHP HydroPerfection Undersink Reverse Osmosis Water Filter System
Filtration: 9 stages
Type: Remineralizing, UV filter
Water Production (GPD): 75
Dimensions: 5 x 15 x 15 inches
Weight: 18.75 pounds

👉 Read the full review
APEC RO-90 Ultimate Series
APEC Water Systems RO-90 Ultimate Series
Filtration: 5 stages
Type: Super capacity filters
Water Production (GPD): 90
Dimensions: 16 x 5.2 x 17.5 inches
Weight: 25 pounds

👉 Read the full review
Express Water Alkaline Reverse Osmosis Filtration System
Express Water Alkaline Reverse Osmosis Filtration System
Filtration: 10 stages
Type: Remineralizing, pH+
Water Production (GPD): 100
Dimensions: 15 x 14 x 5 inches
Weight: 27 pounds

👉 Read the full review
Global Water RO-505
Global Water RO-505 5-Stage Reverse Osmosis System Water Quality Filter
Filtration: 5 stages
Type: Standard, quick-connect
Water Production (GPD): 50
Dimensions: 14 x 5 x 16 inches
Weight: 17 pounds

👉 Read the full review
Greatwell 400 GPD
GREATWELL 400 GPD Tankless Reverse Osmosis (RO) Water Filtration System
Filtration: 3 stages
Type: Compact design, under sink
Water Production (GPD): 400
Dimensions: 11 x 8 x 15 inches
Weight: 19 pounds

👉 Read the full review
NU Aqua Platinum Series
NU Aqua Platinum Series
Filtration: 5 stages
Type: Standard, under sink
Water Production (GPD): 100
Dimensions: 16.9 x 16.5 x 16.3 inches
Weight: 20 pounds

👉 Read the full review
Olympia Water Systems OROS-50
Olympia Water Systems OROS-50
Filtration: 5 stages
Type: Standard, under sink
Water Production (GPD): 50
Dimensions: 16.5 x 16.5 x 19.7 inches
Weight: 24 pounds

👉 Read the full review
Whirlpool WHER25
Whirlpool WHER25 Reverse Osmosis (RO) Filtration System
Filtration: 3 stages
Type: Standard, under sink
Water Production (GPD): 18.46
Dimensions: 4.7 x 12.2 x 13 inches
Weight: 12.7 pounds

👉 Read the full review
Brondell Circle Reverse Osmosis System
Filtration: 4 stages
Type: Under sink, non-electric
Water Production (GPD): 38
Dimensions: 13.8 x 9.2 x 16.5 inches
Weight: 14.6 pounds

👉 Read the full review
AQUA TRU Countertop Water Filtration System
AQUA TRU Countertop Water Filtration Purification System
Filtration: 4 stages
Type: Countertop
Capacity: 1 gallon, 3 quarts
Dimensions: 18 x 18 x 15 inches
Weight: 22.9 pounds

👉 Read the full review

Best Reverse Osmosis System Reviews 2020

1. Waterdrop RO

Waterdrop RO reverse osmosis system review

The Waterdrop RO is a 400 GPD fast flow tankless filtration system that effectively removes most common contaminants from drinking water, including fluoride, limescale, heavy metals and other total dissolved solids.

With a 1:1 pure water to drain ratio, this efficient water system works faster and wastes a smaller quantity of water during the RO process than other reverse osmosis filters. The system doesn’t use a storage tank, preventing secondary water pollution, but produces pure filtered water immediately at the touch of a button, ready for drinking.

The unit can be fitted easily in an under sink area, leaving more cupboard storage space. The system’s internal pump produces water at a rate of 400 gallons per day, filtering a cup of water in around 12 seconds.

The Waterdrop RO contains 3 filters that combine to provide 7 stages of filtration. The system’s pre sediment and carbon block filter delivers the same functions as these filters separately, eliminating larger sediment and dirt, sand, salt, and chlorine from water.

The reverse osmosis membrane is, as stated by the manufacturer, equal to more than three stages of filtration. The activated carbon block filter returns beneficial minerals to the water, improving taste.


  • Tankless, on demand filtration
  • Space-saving design
  • Built in  booster pump


  • Remineralization filter adds small quantities of magnesium and calcium
  • May take slightly longer to fill larger bottles or jugs
  • Higher price point

Read the full review: Waterdrop RO


APEC ROES PH75 review

The APEC ESSENCE ROES-PH75 is a 6-stage reverse osmosis system that removes up to 99% of bacteria and other impurities from drinking water.

The unit consists of a 3-stage pre-filter set, a lead-free faucet, and a water storage tank amongst other features. To improve the filtered water’s alkalinity and taste, the APEC Essence also includes added calcium minerals from a food grade calcium alkaline inline filter.

With a 2 year extended manufacturer’s warranty, this reverse osmosis system comes with all of its parts, and provides easy-to-follow instructions to guide you through the installation process. It has a 1:3 water ratio, slightly higher than the standard 1:4 ratio that applies in general to reverse osmosis water filtering systems.

The 6 stages of filtration include a pre-filter to remove sediment, carbon filters to remove chemicals and odors, a semi-permeable reverse osmosis membrane for removing up to 99% of total dissolved solids, a final carbon filter for removing potential odors from tank storage, and an alkaline filter to re-add calcium carbonate to the water.

The APEC Essence is a simple, cost-effective water filtration unit for anyone who wants to improve the cleanliness of their water while still maintaining the alkaline taste. I


  • Simply DIY installation
  • FDA certified components
  • Additional alkaline remineralizing filter
  • Easy connect to refrigerator


  • May need additional booster pump 
  • No air gap faucet

Read the full review: APEC ROES-PH75

3. iSpring RCC1UP-AK

iSpring RCC1UP-AK 7-stage review

The iSpring RCC1UP-AK is a superior quality reverse osmosis system that uses 7 stages of filtration to remove contaminants and remineralize water for alkalinity.

It removes up to 1,000 harmful contaminants and impurities from water, including chlorine, hormones, asbestos, lead, sodium and more.

With a high efficiency booster pump, the iSpring RCC1UP-AK applies additional pressure, minimizing backflow that can often lead to slower pure water production in other RO systems. This ultimately reduces water waste during the RO process and helps the water storage tank to fill to capacity at a faster rate.

This water filter comes with an advanced UV light kit, which inactivates up to 99% of bacteria and viruses from contaminated water sources. This makes it possible to use well, lake and stream water in the iSpring RCC1UP-AK with the peace of mind that the RO water produced will be clean and safe for drinking.

The iSpring RCC1UP-AK fits under a standard kitchen sink and is purchased with all parts included. The system includes push to connect fittings and color coded tubing to speed up assembly. 

The system’s filtered water to water waste ratio is 1:3 – for every 1 gallon of water that is produced, 3 gallons are lost. This is a slightly more efficient ratio than the standard 1:4 RO ratio. Filters should be replaced once a year to maximize efficiency, and are available at factory direct pricing.


  • Built in booster pump
  • Alkaline remineralization filter
  • Built in UV filter


  • More complex installation
  • No option to remove remineralizing filter

Read the full review: iSpring RCC1UP-AK

4. Home Master TMHP HydroPerfection

Home Master TMHP HydroPerfection​ review

The Home Master TMHP HydroPerfection is an under sink reverse osmosis system that uses advanced filtration and purification sages to remove up to 98% of total dissolved solids from drinking water.

With advanced, long lasting filters, the Home Master TMHP HydroPerfection removes common water contaminants like iron, chemicals, heavy metals and other sediment. The system’s filters can produce 2000 gallons of water before they require changing.

While other RO systems usually require a UV filter to be purchased separately, the Home Master TMHP HydroPerfection includes a built-in UV light to destroy microorganisms in water without the use of harmful chemicals. The filter makes it possible to use this system for standard household water or well water, and can treat water without changing its chemistry.

The Home Master TMHP HydroPerfection remineralizes its produced water, adding calcium and magnesium twice during the purification process for better tasting, less acidic water.

The system includes a permeate pump that increases pressure, preventing the backflow of water that slows down other systems and leads to increased water wastage. This pump allows for water to be produced at a much faster rate, refilling the storage tank more quickly. The waste to pure water ratio in the standard system is 4:1, or 1:1 with permeate pump.

This system provides nine stages of filtration, purification, sterilization, and enhancement to thoroughly clean water and remove impurities and contaminants.


  • Thorough filtration ideal for treating well water
  • Remineralizing filter adds calcium & magnesium back to filtered water
  • Simple installation DIY


  • Additional number of filters makes for bulkier size
  • Higher price point

Read the full review: Home Master TMHP HydroPerfection

5. APEC Water Systems RO-90 Ultimate Series​

APEC RO-90 review

The APEC Water Systems RO-90 Ultimate Series Top Tier is a certified reverse osmosis water filtration solution for providing ultra-safe pure drinking water.

Consisting of a super capacity sediment filter, two carbon blocks, semi-permeable reverse osmosis membrane, and refining coconut carbon filter, this water filtration system combines five total stages for optimal water filtration.

Designed, tested and assembled in the US, the APEC Water Systems RO-90 Ultimate Series Top Tier has been certified by the WQA to remove up to 99% of all contaminants in drinking water, including chlorine, arsenic, lead, heavy metals and much more.

With a 2 year manufacturer’s warranty with registration, this RO unit guarantees safe drinking water for better health.

The maximum feed water pressure is 85 PSI, a significantly higher pressure than the advised pressure of 60 PSI, to ensure the fastest and most efficient reverse osmosis for purification with minimal water wastage.

At a size of around 16 x 5.2 x 17.5 inches and weighing 25 pounds, this water system can be fitted easily underneath a kitchen sink. The unit can be laid on its side for more convenient use of space if desired.


  • Simple, color-coded installation
  • Relatively cheap replacement filters
  • 5 comprehensive stages of filtration
  • Lower price point


  • May require an additional booster pump in some situations with low water pressure
  • No remineralization filter included

Read the full review: APEC Water Systems RO-90 Ultimate Series

6. Express Water 10 Stage RO Mineralizing Water Filter

Express Water 10 Stage reverse osmosis system review

Boasting 10 stages of water filtration, the Express Water Alkaline Reverse Osmosis Filtration System produces the cleanest, healthiest alkaline water without the unwanted chemical contaminants and impurities.

This complex RO system doesn’t only remove up to 99% of chemicals and pollutants like arsenic, lead chlorine, fluoride and bacteria from water – it also remineralizes the water with calcium, magnesium, potassium, and other minerals your body needs from healthy alkaline water.

The Express Water Alkaline Reverse Osmosis Filtration System’s simple design makes it easy for users to set up the system without having to waste money on professional installation. The unit’s thorough instruction manual helps users to understand all elements within the system and provides useful information relating to maintenance, cleaning and filter replacement.

With a 1 year guarantee, this reverse osmosis system automatically refills its pure water tank whenever water levels drop below full, without the need to manually refill or activate the system. The system fits in most under sink areas and is most convenient when installed at a kitchen sink.

The unit requires pre-filter replacements twice a year, while the RO membrane, post carbon filter and alkaline filter need to be swapped out once a year. With a quick connect system and a labelled color match guide, it’s simple to understand which component is located where.

The system can produce 100 gallons of water a day, meaning water will always be available to flow from the faucet as per the user’s requirements. The unit’s built-in leak stop valve shuts off water flow if a potential leak is detected.


  • Multiple remineralization filters
  • Simple installation
  • Built in pressure gauge allows you to monitor flow rate easily


  • No option to skip remineralization
  • May require purchase of additional booster pump

Read the full review: Express Water 10 Stage RO Mineralizing Water Filter

7. Global Water RO-505​

Global Water RO-505 5-Stage Reverse Osmosis Filtration System Review

The Global Water RO-505 is a 5 stage reverse osmosis system with 4 extra filters for removing up to 99% of contaminants such as chlorine, bacteria and lead from drinking water.

The filtration unit’s quick connect fittings make for simple and secure installation. 

The system is compatible with a normal household water pressure range of 40 to 80 PSI, with a pressure of 60 PSI providing the least water wastage and the fastest tank refill time. The filters and RO membrane can purify up to 50 gallons of water a day.

Included in the system’s setup are a sediment filter, a GAC coconut shell filter, a coconut shell carbon filter, an RO membrane, and an inline filter. These filters work to remove larger particles of sand and dust, chemicals and odors like chlorine, heavy metals, bad mineral substances, and any other rough tastes and smells from water.

Filters require replacing after every 6 to 12 months, depending on water quality and level of use. It comes with an extra set of filters, so the first replacement will be free.

NSF tested and certified, this system is produced in the US. The system has a water ratio of 1:3, exceeding the standard RO water ratio of 1:4. 

The system uses a flow restrictor to prevent backflow of water through the RO membrane. This improves the efficiency of clean water production and increases the speed of water tank refill. An automatic shut off valve shuts off all wastewater when the tank is full.


  • Pre-assembled allows super easy installation
  • Great value for money
  • 4 extra filters included


  • Large physical size. Measure before purchasing
  • No remineralization filter included

Read the full review: Global Water RO-505

8. Greatwell 400 GPD​

Greatwell 400 GPD Tankless Reverse Osmosis Water Filtration System review

The Greatwell 400 GPD is a tankless reverse osmosis water filtration system that is designed to produce pure drinking water with a wastewater reduction of up to 450%.

Designed seamlessly with a leak-proof water route, easy-change filters and a slim body, the Greatwell 400 GPD can be stored easily in a standard under sink space. With an all-in-one tankless body, this system looks smart and saves countertop or cupboard space.

The RO system produces thorough filtration results with a 3 stage water purification system that removes up to 99% of over 100 contaminants that are often found in unfiltered drinking water, including lead, chloramine, fluoride, bacteria, sodium and viruses.

With a one-year limited manufacturer’s warranty, and lifetime technical support, the Greatwell 400 GPD boasts premium quality components that are designed for efficiency and durability. All materials are FDA approved and meet NSF standards.

The system’s snap-on connections make installation straightforward. The built-in filter change indicator monitors the life of each individual filter and lets users know ahead of time when filters are no longer working as efficiently.

Filters will need replacing between every 6 months and a year, and cost around $100 in total.

The system requires a water pressure of between 30 and 70 PSI to function. Included in the package is a booster pump, which can be used to improve pressure – optimum is around 60 PSI – if water flow is poor. This enables more efficient reverse osmosis, filling the water tank faster and reducing wastewater production.


  • Compact space saving design
  • No external storage tank
  • Extremely simple installation and filter change


  • Lack of storage tank may not be ideal for some users
  • Water is not remineralized
  • May require additional tubing to connect to refrigerator 

Read the full review: Greatwell 400 GPD

9. NU Aqua Platinum Series

NU Aqua Platinum Series review

The NU Aqua Platinum Series is a high capacity 5 stage reverse osmosis water purifier that offers clean, great tasting, healthy water on demand.

The system features high-quality fittings and a designer lead faucet for installation at a kitchen sink. With a flow rate of 100 GPD, this RO unit produces pure drinking water at double the output speed of a standard reverse osmosis system.

For users looking to test the quality of their filtered water, the NU Aqua Platinum Series comes with a PPM meter to test the level of total dissolved solids left in their water after the reverse osmosis process.

The system filters water through 5 different cleansing stages: the sediment filter, the carbon GAC filter, the carbon block filter, the reverse osmosis membrane, and the post filter. These stages combined allow the system to remove up to 99% of more than 1,000 contaminants found in drinking water, including arsenic, lead, fluoride, chlorine and bacteria.

Depending on the pressure of household tap water, the NU Aqua Platinum Series produces RO water at a rate of approximately 1:2, producing 1 gallon of water for every 2 gallons of water wasted.

While this is higher than the standard ratio of 1:4 for most RO systems, the user can purchase an additional booster pump if their incoming water pressure is significantly lower than the recommended 60 PSI. This would improve efficiency, speeding up filtered water production and reducing water waste.


  • Built in PPM meter allows you to monitor TDS
  • High 100 GPD flow rate
  • Helpful video content for installation included


  • No remineralization filter
  • Does not work well with water pressures of 45 psi or below

Read the full review: NU Aqua Platinum Series

10. Olympia Water Systems OROS-50

Olympia Water Systems OROS-50 review

The Olympia Water Systems OROS-50 is an NSF certified 5 stage reverse osmosis water filter for providing clean, high-quality drinking water with minimal total dissolved solids.

With a 3.2 gallon storage tank, this RO unit is designed to produce up to 50 gallons of filtered water per day. The system is compact enough to fit in most under sink cabinets in a kitchen, and can be stored upright or laid flat on its side.

The system features five stages of water filtration: the polypropylene sediment filter, 2 coconut shell carbon block filters, the 50 GPD semi-permeable RO membrane, and the coconut shell post carbon filter.

The first 3 filters will require changing every 6 to 12 months for maximum efficiency. The RO membrane tends to last for around 2 to 3 years, and the post carbon filter around 1 to 2 years. Filters may need changing more regularly with higher daily system usage.

The operating pressure for this system is 50 – 100 PSI. The manufacturer recommends that users measure household water pressure to ensure that it isn’t below 50 PSI, which may result in slower pure water production and increased water waste.

The ratio of drain water to reverse osmosis water in this filter is 4:1. 

The system does not remineralize pure water after the reverse osmosis stage.


  • Great customer support
  • Easy, color-coded DIY installation
  • Dual carbon block filters


  • Does not function well with water pressures below 40 psi
  • No remineralizing filter included

Read the full review: Olympia Water Systems OROS-50

11. Whirlpool WHER25

Whirlpool WHER25​ review

The Whirlpool WHER25 Reverse Osmosis (RO) Filtration System produces clean drinking water with reduced chlorine taste and odor, sediment, lead, chemicals, and other total dissolved solids.

With an extra long-life filter, this system is designed for longer use between filter changes, with an RO membrane that lasts for years. The system’s built-in EX Change Indicator Light notifies a user when filters need changing, ensuring consistently clean water production.

The Whirlpool WHER25 RO system features a space-saving design with a small footprint that won’t take up too much under sink space. The system can be connected to a coffee machine, refrigerator or ice machine to provide quality drinking water to every taste.

Users looking for quality assurance will appreciate that the Whirlpool WHER25 is USA-built and NSF certified, meaning it has been third party tested to ensure it performs as advertised by the manufacturer.

When it’s time for a filter change, the user does not need to switch off water supply to get the job done. The system features a WHEERF pre and post filter, which require changing every 6 months, and a WHEERM membrane, which should be changed every 2 years.

These filters remove chlorine, lead, chemicals, sediment, microbial cysts and other total dissolved solids from drinking water. Take note that the system also removes calcium and magnesium minerals, which some users may prefer in their water.

The system operates with a 1:4 filtered water to wastewater ratio.


  • Fewer filters creating less hassle during maintenance
  • FDA approved
  • No tools required for installation


  • Not as efficient as other systems
  • Users less mechanically inclined may need to hire a plumber to assist in installation
  • Larger physical size takes up lots of under sink space

Read the full review: Whirlpool WHER25

12. Brondell Circle Reverse Osmosis System

brondell circle review

The Brondell Circle Reverse Osmosis System is a sleek, modern reverse osmosis system that produces high quality filtered drinking water while minimizing water waste.

With four separate filters, this system is designed to deliver optimum water filtration, removing industrial and harmful chemicals, including pesticides, herbicides, fluoride, lead, radium, a number of other chemicals, and any bad tastes or odors from water.

Containing a patented water saving technology, the system’s smart valve eliminates back pressure, which is the biggest cause of inefficiency in most standard reverse osmosis systems. This helps the filtration unit to produce a larger quantity of water with less water waste. As well as saving money, the user can also benefit from faster tank refills for ultimate convenience.

Easy to install and maintain, with everything needed for installation included, the Brondell Circle Reverse Osmosis System is relatively compact in design and fits easily in the space underneath a kitchen sink. 

The faucet’s built-in LED filter change indicator can alert a user to when a filter needs changing to ensure the unit works efficiently for longer. 

It’s recommended that filters are changed every 6 to 12 months, depending on level of use and water type. The tank requires flushing before initial use, but no additional cleaning is needed.

For an even more efficient RO process, this filtration system has a flexible reservoir that expands and contracts to provide a consistent water flow rate, helping to fill the filtered water tank faster without the need for a booster pump.


  • One of the most efficient systems available
  • Compact design& simple installation
  • Automatic filter flushing


  • No remineralization filter
  • May not fit under all sinks. Measure before purchasing

Read the full review: Brondell Circle Reverse Osmosis System

13. AquaTru Countertop Water Filtration Purification System

aquatru review

The AquaTru Countertop Water Filtration Purification System  is a NSF certified water purification treatment for the removal of toxins, hormones, microplastics, carcinogens, and other contaminants from unfiltered drinking water.

Consisting of four filter stages, including the all-important reverse osmosis process, this RO water system is convenient for both home and office use, and takes just minutes to set up.
While most reverse osmosis units require self-assembly, the AquaTru requires no plumbing or installation, and is one of the most convenient countertop water filtration solutions available. This RO system costs considerably less than a standard reverse osmosis system, while delivering the same quality of clean, pure water.

The AquaTru Countertop Water Filtration System comes with filters that last between 6 months and 2 years. There’s no need to guess at when filters require changing – the machine’s digital display will let you know when it’s time. Sleek and compact in design, this reverse osmosis system ticks all the boxes when it comes to visual aesthetics.

With a dispensing button and enough space to fit a standard tall glass, this filtration system offers a faster and more convenient reverse osmosis water alternative. The AquaTru goes beyond filtering water; it purifies it for the freshest taste and most comprehensive removal of contaminants.

Compared to other under the sink RO systems, which usually work off a 1:4 water ratio, the AquaTru is more efficient, discarding only around 25% of water as part of the reverse osmosis process. This ensures filters can continually flush out, extending their life.


  • 3-minute setup
  • Sleek visually appealing design
  • Lower price point
  • More efficient


  • Much smaller holding tank than traditional system
  • Les filtration stages than other systems
  • No remineralizing filter

Read the full review: AquaTru Countertop Water Filtration Purification System

Reverse Osmosis System Buyer’s Guide

We know how difficult it can be deciding whether or not you need to install a reverse osmosis system in your home or not. And once you make that decision, how to sift through the numerous products on the market to find one for your specific needs.

We cover everything you need to know to help you make the most informed decision.

If you’re considering buying a reverse osmosis system, you’ll need to learn a lot before you can go ahead and make a purchase.

You’ll first need to understand exactly how reverse osmosis works, and how a reverse osmosis water filtration system might be relevant for you. You’ll also want to know the basics about under sink reverse osmosis, and how a system is installed.

Finally, it will be good to understand the factors that might affect, and what makes the best reverse osmosis system, if performance and value for money are important to you.

There’s no need to spend hours trawling through forums and Google-searching the specifics when we’ve covered everything you need to know in one single buying guide below.


Reverse Osmosis: The Basics

Let’s first take a look at exactly how the reverse osmosis filtration process works.

This type of purification involves removing the contaminants from unfiltered water to be left with nothing more than fresh, filtered water.

The unfiltered water is forced through a semi-permeable membrane, which has small pores that trap dissolved solids like salt, stopping them from passing through. Water molecules are small enough to pass through the pores, so only clean water makes it out of the other side.

The impurities that are left over are sent straight down the drain, leaving only delicious, pure drinking water.

The best RO filtering systems push water through a number of different membranes for optimal results. This helps to remove as many different types of impurities through a combination of chain processes.

Some impurities require different types of filtration than others, which is why a number of filters have been developed for a more intensive overall treatment.

reverse osmosis process

Let’s make things a little clearer with a simple example of how the reverse osmosis process works. Imagine we have a water solution that contains a significant salt concentration.

The salt particles are what we need to remove to make the water drinkable and clean. In scientific terms, the water is referred to as the “solvent”, and the salt is referred to as the “solute”.

The only way to separate this salt from the water, in the case of reverse osmosis, is to use a semi-permeable membrane.

This membrane sits directly between two water storage units, and consists of thousands of tiny holes that are just big enough to allow the water to pass through, but block the salt from making it to the other side. In this way, the water and the salt are separated, leaving the water that passes through salt-free and safe to drink.

During reverse osmosis, while the water that’s left over begins to get pretty crowded with salt, more and more pure water will be forced from this side over to the clean water side, leaving a high concentration of the solute on one side, and only the solvent on the other side.

Enough pressure needs to be applied to counteract the osmotic pressure from the side containing pure water, so that reverse osmosis can effectively separate water from unwanted particles at a fairly efficient rate.

We’ll cover the reverse osmosis process in more depth later on in this guide.

What’s Wrong With Unfiltered Water?

Unfiltered water is generally considered safe to drink but it contains a number of harmful chemicals and pollutants that some scientists believe could cause damage to our long-term health.

We put our trust in water treatment facilities to remove the worst of contaminants from water, but their regulations allow for some to remain. Some chemicals, such as chlorine, are even added to water to disinfect it, and remove any micro-organisms that it may pick up during its journey to your home.

In most unfiltered water, you’ll find a combination of contaminants including fluoride, chlorine, lead, arsenic, radioactive substances, copper, PFOA, and pesticides. These can cause a number of underlying health concerns, including fatigue, cognitive decline, digestive and gastrointestinal issues, and even some forms of cancer and brain damage.

Worryingly, we still don’t know how drinking unfiltered water might affect us in the long run. Drinking water that’s been filtered in the reverse osmosis filtering system reduces the risk of all number of health problems, some of which scientists may not even be aware of today.

Benefits Of Reverse Osmosis

Reverse osmosis is one of the most popular water filtration treatments, and boasts a number of benefits that puts it ahead of alternative methods. The advantages of filtering with one of these systems include the following:

Removes Impurities

Water that’s been treated can contain impurities and pollutants, including pesticides, nitrates, bacteria, fluoride and even arsenic.

The only way to remove these impurities is by filtering them – and reverse osmosis is a method that guarantees clean, pure water.

Most RO filter systems also contain carbon filters, which remove chlorine and chloramines. These disinfect water as it moves through pipes to your home, but may cause a number of health concerns when ingested in larger quantities

Improves Taste

There’s no taste quite like that of clean, pure water. You might not realize just what effect unfiltered water’s impurities can have on its taste until you try a sip of filtered water – and then there’s no going back.

There may be a number of reasons why your unfiltered water tastes funny, the worst – a rotten egg sort of flavor – being down to the water’s hydrogen sulphide content or various bacteria.

The best way to get rid of this taste is to get rid of its source, filtering out the bad stuff with a reverse osmosis filtration system.

Easy to Maintain

The problem with some water filtration systems is that they can be a nightmare to clean, and even worse if something needs fixing.

Because a RO system is fairly simple in design, you won’t need to worry about taking everything apart for a stringent regular cleaning process, and nor will it be a fuss to replace something when it’s seen better days.

Nobody wants to spend hours maintaining their water filtration equipment, and with an RO system, you won’t need to.


You might not consider a reverse osmosis water filtration system to be your cheapest purchase, but when you weigh it up against the alternatives, the cost is more than worth it.

You’ll no longer need to spend money buying your own filtered water from the supermarket, which, if you do the math, totals up to be quite a significant yearly cost.

You’ll find that reverse osmosis filtering provides even better-quality water than filtered bottled water at a fraction of the price.

Contaminants Removed By Reverse Osmosis Filters

When it comes to any type of water filtration, the more effective treatments will be proficient in removing a higher percentage of total dissolved solids from the water.

A water’s TDS, or total dissolved solids is the number of substances, both organic and inorganic, that the water contains.

Typically, these include a mixture of minerals, salt, pesticides, cations, metals, and other substances that might have made it into your drinking water, depending on how it is treated locally and how it makes its way to your home.

It is impossible to find a water filtration system that can fully remove 100% of total dissolved solids from water, as the process would take far too long, and wouldn’t be considered a good value for money from a consumer’s perspective.

However, reverse osmosis is a particularly effective means of water filtration that can generally remove at the very minimum 75% of total dissolved solids from water. The best RO water filtration systems may even be able to remove between 90-99% of all total dissolved solids from water.


Reverse osmosis is effective at removing all contaminants that you’ll find in unfiltered drinking water, which may have dissolved into the water before, during or after the water treatment process.

Chemicals and contaminants most commonly enter unfiltered drinking water from surface run-off, sewage, natural sources, during water treatment, and from the piping the water is transported to your home in.

Just a few of the impurities that reverse osmosis can remove include copper, lead, chromium, salt, fluoride, sulphate, calcium, nitrate, potassium, chlorine, phosphorus, arsenic, bacteria and some pesticides, and any other suspended solids.

The majority of RO systems for home or business will enable you to monitor your water quality and view recorded data to determine the efficiency of the filtration process.

It’s worth noting that some pesticide molecules are smaller than water. This means these particles can pass through the semi-permeable membrane, making it impossible for the initial reverse osmosis process to filter them out completely.

However, a number of modern reverse osmosis systems now include an additional carbon filtration stage which removes any remaining pesticides from the water prior to drinking.

All RO systems also run the unfiltered water through a pre-treatment to ensure the filtration process runs as efficiently as possible.

Considerations When Purchasing An RO System

Water Source

Your water source might have an effect on the reverse osmosis process, depending on the type and number of contaminants it contains.

Generally, the more contaminants your unfiltered water contains, the more difficult it will be for a semi-permeable membrane to filter out these contaminants effectively.

Certain types of contaminants may also be more difficult to remove because of their particle size in relation to the water particles.

Water Usage

You can expect that a reverse osmosis unit for a household or small business, used for the purpose of producing pure drinking water, will filter more water than you consume.

You’ll be fine to turn on the faucet whenever you need a drink, as once you’ve used a certain amount of water, your reverse osmosis unit will get to work creating more clean water to replace what’s been lost.

However, if you’re planning to use a reverse osmosis unit to produce pure water for commercial purposes, you might find that one system is not enough to filter the water at a desired rate.

It’s best to speak to an expert in any situation where you might want to use a reverse osmosis treatment for your business, as they can advise you on exactly what will meet your requirements.

Average US Household Water Usage

Water Pressure

The reverse osmosis process can only work effectively when enough pressure is applied to force the water through the semi-permeable membrane to the other side.

Actually, the pure water on the other side wants to move back through the membrane into the impure side in the natural process of osmosis, so pressure needs to be high enough to counteract this and force new water through the membrane.

Low water pressure, then, will lead to a reduced production of water, and may even cause the semi-permeable membrane to become ineffective more quickly.

It’s recommended that a RO filtration system has a pressure of around 60 PSI for optimal functioning. If you want to get the best value for money from your system, it’s worth looking for one that boasts a pressure around this number.

Storage Capacity

When it comes to storage, all RO systems are slightly different in what they can hold. You’ll find that some units have tanks that can store up to 75 gallons of filtered water – but keep in mind that paying more for a bigger tank isn’t always necessary.

If you think you’re going to need 75 gallons of water at a given time, then by all means go for a larger tank. But keep in mind that your tank will consistently replenish whatever you use, so there’s no need to worry about it running out.

Your reverse osmosis system will be able to refill at a rate of around a gallon per hour, which, for most consumers, is more than enough to keep them going.

Remineralization Needs

Some people enjoy being able to drink certain minerals in water, which can be fairly beneficial to our health. These include magnesium and calcium, both of which we need to maintain good bone health, ward off diabetes, prevent headaches, provide relief from anxiety symptoms, improve heart health, and much more.

While we can get magnesium and calcium from other sources, obtaining them through drinking water is an easy way to ensure we’re getting our daily mineral requirements.

As reverse osmosis removes all minerals from your water, you’ll have to look at remineralizing your water if certain minerals are important to you. You can do this by adding a few mineral drops to your water, or adding an extra filter to your RO system. Another simpler method is to take calcium or magnesium supplements in tablet form to make up for what you might be missing from your water.

Replacement Filters

Reverse osmosis requires some basic maintenance if you want to keep your system working at its best. Depending on the quality of your filters, you might need to change them fairly frequently.

Generally, it’s recommended that you change your sediment filter, carbon filter and polishing filter at least once a year, and your semi-permeable membrane every two years.

Always look at specific details relating to your reverse osmosis unit in case you need to replace your filters more or less often.

Remember that the higher quality the product, the less often you’ll need to change the components – although all will experience some wear-and-tear in the inevitable future.

reverse osmosis system replacement filters

Filter Certifications

NSF Certified

NSF International logo

NSF International is an independent body that was established after a significant influx in the development of products for improving water quality at home. It helps users to know when home water treatments are as safe and high performing as claimed by the manufacturer.

NSF goes by the American National Standards Institute (ANSI) standards development process.

With NSF certification, a manufacturer can assure the public that a reverse osmosis water filtration product is safe, effective, and complies with the NSF technical requirements. To achieve NSF certification, an RO system must undergo product evaluation and lab testing, manufacturing inspection, product sampling, review of test results, and following on, an annual inspection and retesting.

WQA Certified

water quality association logo

Also an independent organization, the WQA offers certification for water treatment industry professionals. The WQA’s Gold Seal Certificate shows that a water system is constructed by safe materials, backed by test data, and will perform correctly under normal usage conditions.

By voluntarily undergoing a credentialing process, a manufacturer demonstrates commitment to maintaining high professional standards and improving customer experience relating to a reverse osmosis filtration product.

A professional certification by the WQA offers a number of advantages to a water filtration manufacturer, and lets customers know when a product can be trusted.

Certification is accredited after the manufacturer completes an appropriate work course, passes a comprehensive exam, and agrees to abide by the WQA Code of Ethics for the Water Quality Improvement Industry.

Certification lasts for a total of 3 years.

How Do Reverse Osmosis Filters Work?

Let’s look at reverse osmosis filters in a little more detail. The process begins in the area of the unit that’s connected to the cold water system in your house. The water comes in at this end of the unit, where it can be filtered before it reaches your taps for drinking.

The untreated water first flows through a combination carbon and 5-micron sediment filter. The role of the carbon is to remove chemicals from the water, most commonly the likes of chlorine, or fluoride. In well situations or in rural applications, often the chemicals in the water are things like herbicides or pesticides, which may have entered the water via surface run-off.

At the same time, the 5-micron sediment filter removes the larger portions of the sediment in the water, which could damage the semi-permeable membrane in the later stages of the filtration process.

From there, the water then passes through another sediment filter, this one a 1-micron sediment filter. The role of this filter is to filter the water down significantly more, helping to produce a cleaner, purer product. It’s finally time for the water to pass through the membrane.

reverse osmosis filter

The semi-permeable membrane is very dense, making it very difficult for the water to get through. It filters out all the larger particles, leaving only high-quality drinking water. The process is continuous – water flows in one end and flows out the other end, and while the reverse osmosis water is being made, the impure water is flowing out through a drain line. The semi-permeable membrane is flushed with water at a constant rate, enabling it to remove all of the impurities and flushing them off to the drain.

When the RO water reaches the tank for storage, it can be used by you when you turn on your faucet. When this happens, the water passes from the tank through one last carbon filter, which acts as a precautionary filter in case the water has picked up any odors in the tank. Finally, the water will flow to the separate faucet that you’ll have installed at your kitchen sink as a feature of your reverse osmosis unit.

Whenever you switch on your faucet, the RO water will flow immediately from the tank and come out of the tap. Any water that is lost in the tank will be refilled from the system

We’ll cover more about each stage of the reverse osmosis process below.

The Reverse Osmosis Process: Step By Step

Typically reverse osmosis filtration follows a basic 5 step process. When you see a product claiming more than 5 steps, it means the producer has split one of these 5 into sub-steps. Here is a quick overview of how the process works.

  1. Sediment removal – Before water can pass through the semi-permeable membrane in reverse osmosis, it needs to undergo sediment removal. This is the first treatment that your unfiltered drinking water will receive once it makes it into your filtration system. The bigger particles will be removed from your water at this stage, including sand, dirt and rust. These could potentially damage or clog up the semi-permeable membrane and other parts of the system, so they need to be cleared from the water before it can pass onto the next stage of filtration.
  2. First carbon filter – The first carbon filter will remove impurities that would otherwise damage the semi-permeable membrane, such as chlorine and other chemicals. All RO filter systems for home contain at least one carbon filter for essential removal of these particles. Carbon filters can also improve the scent and taste of the water, and remove some pesticides and smaller particles that might be able to pass through the semi-permeable membrane along with the water.
  3. Second carbon filter – Not all RO filtration systems contain multiple carbon filters, but it’s becoming more common for a unit to have at least a second filter for maximum efficiency. If your water has a higher carbon quantity, a second carbon filter will help to ensure that all particles are removed before the water can pass through into the area containing the semi-permeable membrane. There may also be a final carbon filter stage between the storage tank and faucet to remove any taste or odour the water might have picked up in the tank prior to drinking.
  4. Reverse osmosis membrane – The reverse osmosis membrane is at the heart of any reverse osmosis water system. Once the water has had larger sediment and particles removed in the sediment and carbon filter stages, it will be able to pass through the semi-permeable membrane the most effectively. Because the membrane contains thousands of tiny holes, the water molecules can pass through when pushed towards the membrane under pressure, but any larger particles stay behind. Only clean water remains on the other side of the membrane.
  5. Impurities removed – While the water is flowing through the semi-permeable membrane, at the same time, the impurities are removed, where they flow straight to the drain. The impurities flow out of the RO water filter system through a separate pipe, so there’s no risk of the particles finding their way back into the filtered water. The speed at which the impurities are removed generally depends on the pressure applied to the water passing through the semi-permeable membrane, and the temperature of the water in your system.
  6. Remineralization – Reverse osmosis is one of the most effective means of water filtration, and for this reason, the water that’s left over for drinking is incredibly pure. While you might be happy to drink this water – and it’s perfectly safe to do so – you may want to remineralize your water. You can look to add a remineralization filter to your reverse osmosis system, which can add in healthy minerals like calcium and magnesium, balancing the water’s pH and improving its taste.
  7. Optional step: UV treatment – One optional addition you can make to your RO filter system is to add UV treatment. The purpose of this treatment is to make sure your water is bacteria-free, which reverse osmosis can’t do on a continual basis. You can easily add an ultraviolet light to the output from your filtration system, and the filtered water would flow up through the light before reaching your faucet in your kitchen sink, where it would come out of the tap. When the ultraviolet light is switched on, it kills any bacteria that flows through it, making it even cleaner and safer to drink.

Most people won’t need to UV-treat their water, because the water that comes into your home has already been treated to make it safe to drink. If you’re using well or surface water for drinking, however, or you simply want to further purify your water, you’ll find a UV light to be a handy addition to your reverse osmosis treatment system. You can purchase one to add on yourself, or enquire about them when you’re arranging for your RO filtering system to be installed.


Reverse Osmosis Water Efficiency Ratio

The water efficiency ratio of your RO system determines how much of your water is being filtered through the semi-permeable membrane in comparison to how much wastewater containing contaminants is being lost down your drain. It goes without saying that the less water is wasted during the reverse osmosis treatment, the more efficient a unit is.

You won’t find a set water efficiency ratio for RO filtering systems generally, as there are a number of varying factors that affect how well each different system works. The better-quality a system’s parts, and the higher the pressure applied to the water passing through the semi-permeable membrane, the less water will be wasted.

You can expect most RO systems to work on a 4:1 ratio, meaning that for every 1 gallon of water that’s filtered, 4 gallons of wastewater will pass down the drain. However, this isn’t to say that all reverse osmosis filtering systems operate on this ratio. A number of more modern systems have been designed to minimize water wastage, and are far more economically effective than previous models.

If you want to get the most back from your RO water filter system, you’ll need to look for a unit that is well-designed and operates at a pressure of 60 PSI. Anything below 40 PSI is considered insufficient, and will produce far more wastewater, as there won’t be enough power to push water through the semi-permeable membrane.

The Components Of A Reverse Osmosis Filtration System

Even with some knowledge about the reverse osmosis process, it’s hard to imagine what a reverse osmosis filtering system actually looks like. You’ll find that most systems are similar in design, and contain the same sorts of components.

When you’re looking to purchase an RO filter system yourself, the biggest difference you’ll find is in the quality of the system and the individual parts that make it up. Generally, you can expect that the cheaper the parts used, the less effectively the system will work.

Here are the key components of any reverse osmosis system:

components of a reverse osmosis system
Source: Amazon.com

Pre Filter

A pre filter is essential in all RO systems. This is where the water from your pipes will enter before it is filtered. The pre filter process is necessary for the protection of the components that are needed for the actual reverse osmosis. It removes larger grains of sediment from the water, like dirt, which could obstruct the system and prevent it from working as well.

Semi-Permeable Membrane

Undoubtedly the most important feature of the reverse osmosis filtering system is the semi-permeable membrane itself. This is carefully designed to trap the unwanted elements of unfiltered water, including contaminants like pesticides. Treated water passes through this membrane before entering a pressurized tank for storage.

reverse osmosis semipermeable membrane diagram

Post Filter

Just as all RO filtration systems have a pre filter, they also have a post filter. Post-filtering takes place once the water leaves the pressurised tank, but before it enters your taps for drinking. The process gives the water one final treatment, which usually removes any remaining carbon, helping to give water the best appearance and taste possible

Shut-Off Valve

Without a shut-off valve, a RO filtering system would struggle to function as efficiently. Shut-off valves are usually automatic, and detect when the water storage tank is full, preventing more water from entering. Once you’ve drained some of the tank’s water supply, the automatic shut-off valve will sense that there’s room for more water, and allows more water to enter the tank, sending any contaminants straight to the drain.

Flow Restrictor

Believe it or not, the speed at which water flows through an RO filtration system can affect how much water actually passes into the storage tank after filtration. This is because without a flow restrictor, the water would simply take the easiest route – in this case, down the drain – rather than through the semi-permeable membrane. The flow restrictor applies pressure to the water and pushes it through the membrane.

Storage Tank

All RO filter systems have their own storage tanks for holding treated water before use. These tanks can generally hold around three gallons of water, although you may find some that can hold more than that.

Remineralization Filters

Not all reverse osmosis systems contain remineralization filters, but they’re becoming more popular nowadays. Remineralization filters are used to replace some of the healthier minerals that are removed during the reverse osmosis treatment.

Because reverse osmosis removes all impurities from water, there’s no way to prevent harmless minerals like calcium, magnesium, iron and zinc. These minerals are essential for maintaining good health, assisting in growth and development, maintenance of immune function, and helping our bones and muscles to stay strong.

We can get calcium, magnesium, iron and zinc from our food, but it’s handy to be able to obtain them from our drinking water, too – which is where remineralization filters come in handy.

The remineralization process allows for minerals to be added back into the filtered water before it reaches the tank for storage. It can be quite easily attached to your RO filtration unit, and contains a number of minerals that flow back into the water as it passes through. The temperature and the pH of your water once it’s completed the reverse osmosis stage will determine how many minerals are dissolved back into the water, and how effectively.

reverse osmosis remineralizing filer
Source: Walmart.com


When you get a reverse osmosis filtering system installed, you’ll usually have to switch up your faucet for one that comes with your system. This is normally fitted in your kitchen sink for convenience.

Air Gap Faucet

An air gap faucet is sometimes used for providing a literal air gap for the reverse osmosis unit’s drain system. It’s handy for stopping water from being siphoned back into your RO filtration system through the system’s drain connection. The air gap sends the drain water from the reverse osmosis unit up into a small trough at the underside of the faucet, where it then passes to the other side of the faucet stem and passes through a special tube into the drainpipe.

An air gap faucet requires multiple tubes, and for that reason, you’ll need to have a larger hole made in your sink to install it. Installation may also take longer, as it’s a little more complex.

It’s worth being aware that an air gap faucet is not essential, and actually, non-air gap systems tend to be more modern nowadays. There are several issues with air gap faucets that make them the less desirable choice – as well as costing more to install, they frequently leak out reverse osmosis waste water onto your sink or counter top if the drain tube becomes even slightly blocked, and they can produce an undesirable gurgling noise while they’re in action.

air gap faucet


Permeate Pump

The purpose of a permeate pump is to improve the efficiency of water filtration in a RO filtering system. Without this pump, too much water would pass straight down the drain, and the water that passed through the semi-permeable membrane would do so at a slower rate. A permeate pump itself can help to prevent up to 80% of wastewater.

The permeate pump stores the water containing impurities in a chamber and uses it to produce energy, which speeds up the production of pure water during the reverse osmosis process. It helps to push the water into the storage tank, preventing it from pushing back against the semi-permeable membrane

Electric Pump

Electric pumps work very similarly to permeate pumps, but are different in design. The device uses a pressure switch to monitor water pressure in your system’s water storage tank, and turns on a pump to increase water pressure when necessary.

Not all RO filter systems will need an electric booster pump, as they might already have enough water pressure for the reverse osmosis process to work properly. However, if your water pressure falls below 40 PSI and you want less water waste and more efficiency, an electric pump will help you fill your water storage tank faster.

What Might Affect A Reverse Osmosis System’s Performance?

There are a number of different factors that you should take into consideration if you’re looking to get optimum performance out of your water filtration system. Namely, efficiency of operation is affected by the following:

Quality of Components

Cheaper reverse osmosis filtration systems with poorer-quality parts slow down the water filtration process, and may not filter water as successfully as systems with better components. You may also find that a poorer-quality system has a shorter lifespan and requires more maintenance and upkeep.

Water Pressure

The pressure of the water flowing through the system will determine how effectively water passes through the semi-permeable membrane. There needs to be enough pressure for the water to be forced through the membrane, otherwise it may pass straight through to the drain instead. Water pressure that’s too low will cause poor operation.

Water Temperature

There’s not a lot you can do about the temperature of the water that flows through your pipes, but usually, the colder the water, the longer the filtration process works. This shouldn’t be enough of an issue to affect your daily water-drinking habits

Unfiltered Water Contaminant Contents

The contents of your unfiltered water as it reaches the system will also affect water filtration somewhat. The more contaminants a water sample contains, the harder an RO filter will have to work, which may impact performance quality. The same goes for the type of contaminants in the unfiltered water – some are more difficult to filter than others.

Installation & Maintenance of Your Reverse Osmosis Filter System

While you might prefer to hire a plumber to install your RO system for you, it isn’t too difficult to do yourself. You can save a lot of money from doing this, and if you’re feeling up for the job, follow the simple step by step system installation process below.

If you’re looking to install a standard under sink reverse osmosis system, these simple steps will help you to do the job correctly. In the majority of cases, your RO filter system should come with instructions for installation, but if you’ve not yet bought your unit, and want to know in advance how to put it together, this installation guide will come in handy.

Before you get started with the installation, you need to make sure your RO filtering system has all the required parts you need for it to work. Make sure your system has all of its key components, including the storage tank, the reverse osmosis unit complete with filters and semi-permeable membrane, and the new faucet for your sink. under sink reverse osmosis system

You should also make sure you have the required tools on hand to help you carry out the installation properly. You’ll normally need wrenches in various sizes, as well as drill, and a screwdriver and removable screw heads in various sizes. You’ll get a clearer idea of the exact tools you’ll need for the job when you read the instruction manual for your system.

It’s worth giving your own instructions a thorough read before you get started with the installation process. While the instructions should be fairly easy to follow, if you slip up, you may end up causing damage to your RO filter system before you even get a chance to use it.
Here’s an idea of what the instruction manual would include for a standard under sink reverse osmosis unit

Step by Step System Installation

  1. Choose your installation location – Your first task is to find a location that’s most appropriate for installing your reverse osmosis water system. In most cases, the system fits nicely underneath your kitchen sink, but you can choose to put it elsewhere if it suits you more. Make sure you’ve got plenty of room under your kitchen sink to easily fit your filtration system. This might mean removing shelving and re-organizing kitchen products to make installation possible.
  2. Turn off your water – It would be a bad idea to install a filtration system without first switching off your cold water valve. This is usually found under the sink, and is probably connected to copper piping. Twist the valve to stop cold water from being able to flow through the pipes leading to your sink. If you can’t turn the valve off, you’ll need to turn your whole home’s water supply off for the duration of the installation process.
    Connect your system to your cold water line – Before you do anything else, twist your cold faucet “on” to relieve any line pressure. Next, you can get to work connecting your RO filter to your cold water line. Locate the saddle valve clamp and attach to the cold water line. Then adjust to fit to the shape of the pipe, and use a wrench to tighten the bolt and keep the clamp firmly in place. Don’t over-tighten; just apply enough pressure for the bolt not to be loose.
  3. Connect your drain line – At this stage, if there’s noticeable corrosion of your drain line, you’ll want to replace it before you continue with installation. If your drain line is fine, you’re good to go. Drill a hole into the outside wall of your pipe, and attach the drain clamp. Tighten the clamp, again being careful not to go in too hard.
  4. Install your faucet – When installing your faucet, it’s usually a good idea to keep it as close to where your previous faucet was as possible. You want it to look good and work practically from its location, and the area for the faucet base to sit needs to be flat. If you already have a hole in your sink, you don’t need to drill another one. Position your faucet stem inside the hole and make sure the base is in the right location over the sink. Tighten the faucet in place, making sure to align it in the direction you wish to use it (over the sink is the obvious best). Then attach the appropriate tubing to the bottom of the stem.
  5. Put your unit in place – It’s now time to put the unit in the desired location underneath your sink. You might need to hang your system on a wall if there’s no shelf for it to rest on. Connect the units to the piping, and go back for one final check to make sure everything is sufficiently tightened and in place before giving your system a go.

Once you’re sure everything looks good, turn on the cold water valve slowly. Look out for leaks, and if you notice any, turn the water back off and repair them before going again. Your reverse osmosis tank will take several hours to fill, so you’ll need some patience during this period of time. It’s a good idea to continue to check for leaks during the first few hours of use, and make amendments if necessary.

Maintenance and Changing Filters

There will come a time when you’ll need to change your filters in order to keep your RO system working as efficiently as possible.

To change the pre-filters, turn off the system and turn off your cold water valve, then lift the faucet lever to prevent a build-up of pressure in the system. Use a wrench to open the first-stage filter housing, then remove the old filter and replace it with the new one. Finally, hand-turn the housing to close it back up.

If you’re changing your semi-permeable membrane, follow the same instructions as above, turning off the system and your cold water valve, then lifting the faucet lever to prevent a build-up of pressure. Disconnect the tubing from your membrane housing, then remove the cap from the membrane housing and use a pair of pliers to remove the old membrane. Use the same pliers to insert the new membrane and close the cap, turning it clockwise to tighten it.

To change the 5-stage post carbon filter, after you’ve switched off your system and cold water valve, you’ll need to drain the reverse osmosis water tank. It might take around ten minutes for the tank to drain fully. Next, disconnect the output tubing and remove the existing filter from the membrane housing. Replace as necessary and reattach to the reverse osmosis unit.

As well as changing your filters, it’s also a good idea to clean out your system every half a year to a year with hot, soapy water. Make sure you turn off your system and water supply before taking it apart. The tubing and housing can be washed, but don’t wash any of the filters or the membrane.

The Verdict: What is the Best Reverse Osmosis System?

It’s important that you choose the right reverse osmosis water filtering system for your home or business. Make a careful, considered purchase based on reviews, the trustworthiness of the manufacturer, and your own personal requirements. Don’t be afraid to ask more questions if you have them.

Not all RO systems are the same. Some contain a different number of semi-permeable filters, offering a lengthier or shorter water filtration process.

Some may be made more cheaply than others, and some may allow for more water to be filtered in gallons per day. Its best to take these differences into account when you’re considering what best reverse osmosis system is right for you!

Frequently Asked Questions

🛠 How much does a reverse osmosis system cost to install?

You can expect to spend anything between $100 and $300 for an RO system. Don’t pay anything more unless you’re certain you’ve found something really special. If you need to hire a plumber to install your system, there’ll be an extra fee to factor in for the service. After your initial purchase, you’ll need to be prepared to splash out on replacement filters every year, which cost around the $100 mark. These help to keep your whole system running efficiently for longer.

📅 How long does an RO filtering system last for?

The quality of your RO filter system will determine how long it lasts for. If you drink excessive amounts of water, thus use your system more frequently, this can also affect the lifespan of your unit. All RO filters will experience the expected amount of wear and tear over time, so unsurprisingly, they don’t last forever. You might need to replace parts every year or two, such as your filters and storage tank. There’s no need to replace the whole system, only the parts that are worn out.

💦 How much wastewater does reverse osmosis produce?

It’s true that a reverse osmosis filter system generally uses more water than it produces, but in terms of waste, it’s not so bad. You won’t see anything noticeable on your water bill after using a reverse osmosis filtration system for a month or two – it’s similar to your other appliances that use water, like washing machines and dishwashers. When your RO water storage tank is filled to the brim, the tank shuts off, and water stops passing through the semi-permeable filter, so you don’t need to worry about extra wastage.

💲 Does an RO system work better if it costs more?

Not necessarily. While systems containing more expensive parts – and therefore costing more – tend to be more efficient and durable, there are some reverse osmosis filtration systems that cost an inflated amount of money, with no evidence to suggest they’re doing anything other than their competitors out there. If you think a seller is asking for an unfair payment, either avoid them, or enquire about what makes their product so special. Always read reviews and look into the history of a company before making a purchase.

🔬 How important is water mineral content?

There’s been controversy around the mineral content of water for a number of years now. Most people believe that minerals like calcium, sodium and magnesium are good for your health, but some scientists argue otherwise.

Hard water is safe to drink, but it can cause your skin and hair to become dry and irritable. Some studies have linked hard water to dandruff and eczema, and even increased risk of high blood pressure and cardiovascular disease. Generally speaking, there’s not enough evidence to argue for or against it either way, but water mineral content really isn’t as important as it’s made to be. That said, you can always purchase a filter that adds the minerals back into your reverse osmosis water if that’s your preference.

Best RO System Comparison Chart

SystemRelative PriceFiltration StagesTypeWater Production
Waterdrop RO
Tankless400 GPD
$$$6Alkaline mineral pH+75 GPD
iSpring RCC1UP-AK 100GPD
Remineralizing, UV100 GPD
Home Master TMHP$$$$9
Remineralizing, UV filter75 GPD
APEC RO-90 Ultimate Series
Super capacity filters90 GPD
Express Water Alkaline Reverse Osmosis Filtration System
Remineralizing, pH+100 GPD
Global Water RO-505
Standard, quick-connect50 GPD
Greatwell 400 GPD
Compact design, under sink400 GPD
NU Aqua Platinum Series
Standard, under sink100 GPD
Olympia Water Systems OROS-50
Standard, under sink50 GPD
Whirlpool WHER25
Standard, under sink18.46 GPD
Brondell Circle Reverse Osmosis System
Under sink, non-electric38 GPD
AQUA TRU Countertop Water Filtration System$$$4

Countertop54 GPD