Pros and Cons of Reverse Osmosis Water Filtration

Reverse osmosis (RO) is one of the most effective water filtration methods available. A reverse osmosis water filter can remove hundreds more contaminants than most filters, resulting in clean, pure water.

But does its incredible contaminant removal make reverse osmosis an instant favorite? Not necessarily. Like most water filtration solutions, reverse osmosis has its disadvantages, and is better suited to some people than to others.

I’m this article, I’ll be sharing how a reverse osmosis water filter works, and the pros and cons of reverse osmosis technology as an at-home water treatment method.

🌀 What is Reverse Osmosis Filtration?

Reverse osmosis (RO) filtration is the process of sending water through several filter stages, including a semi-permeable membrane.

The semi-permeable membrane is the standout feature of a reverse osmosis water filter, and what sets this filtration method apart from others.

The purpose of reverse osmosis technology is total dissolved solids (or TDS) removal.

⚙️How Does a Reverse Osmosis Water Filter Work?

During the RO process, water is forced at a high pressure against the membrane, which has tiny pores that allow only water molecules to pass through. Particles larger than water rebound off the surface of the membrane. These particles are then washed away down a drain with wastewater.

As well as the semipermeable membrane, reverse osmosis systems also have a sediment pre-filter, which protects the membrane from large sediment particles, and a carbon filter, which removes any contaminants that may have been able to slip through the membrane.

If you’re keen to learn more about the reverse osmosis process, you should find my infographic guide helpful.

Closer look of the reverse osmosis membrane

👍 Pros of a Reverse Osmosis System

If you choose a reverse osmosis system for your water filtration needs, you’ll enjoy the following benefits:

Removes Most Contaminants

Reverse osmosis filters can often remove upward of 99.99% TDS (total dissolved solids) from drinking water. Examples of contaminants removed by an RO system are fluoride, nitrates, sulfates, arsenic, bacteria, and other health-harmful, unwanted impurities.

There are hundreds of potential trace contaminants in our drinking water, and the average carbon filter will only remove a fraction of them. However, with a reverse osmosis system, you know that there’s a high likelihood that the system removes whatever problem contaminants you’re dealing with. This is one of the system’s biggest advantages.

Improves Taste & Odor

Many contaminants in our drinking water affect water’s taste and smell. Chlorine, fluoride, pesticides, and herbicides can give water a chemical taste, while sulfur gives an unpleasant rotten egg odor, and iron gives a harsh, metallic taste.

Using a reverse osmosis water filter removes the contaminants that give water an unpleasant taste or smell, giving better-quality, better-tasting water that you look forward to drinking. You’ll enjoy the advantages of clean water from your own home.

Low Maintenance

Once you’ve installed a reverse osmosis water filtration unit, all you’ll need to keep up with is filter changes. The unit is fully automated and doesn’t require backwashing, regeneration, or manual flushing after installation. For the most part, you can forget all about the unit after you’ve set it up.

Changing the filters in RO systems is easy, and filters can be replaced by anyone. There are usually around three filters to change, including the semipermeable membrane. Some RO systems pack all filtration stages into one or two filters, offering advantages including reduced filter changes.

RO system on a counter with dedicated faucet

Variety of Options Available

There isn’t one set type of reverse osmosis system on the market. You can choose from a variety of options:

These different options come at different price points, and each has its own pros and cons, and unique features. For instance, tankless systems are space-saving, while one of the biggest benefits of systems with a storage container is that you won’t have to wait for the unit to finish filtering before you get access to clean, healthy, contaminant-free water.

You can choose the type of RO water filtration system that best suits your budget, your family size, and your requirements.

Promotes Drinking More Water

If you have great-tasting water at home, you’ll be more inclined to drink when you’re thirsty. Drinking plenty of water can keep you hydrated, and has benefits relating to skin health and energy levels.

Having easy access to delicious water means you’re less likely to hydrate with unhealthier options, like sugary drinks or processed fruit juices.

Person drinking filtered water

Cost Effective

With a reverse osmosis water filter, you’re drinking water straight from your kitchen sink, rather than paying for bottled water. This means you can get the same quality water that you’d get from a bottle, for only pennies per gallon.

Bottled water is something you’ll need to keep on spending money on. If you have a big family, this cost will add up, fast. Reverse osmosis is much more affordable in the long run, as once you’ve paid for the system, you’ll only need to pay to replace the filters once or twice a year. Most RO systems pay for themselves within a couple of years, and after this, the financial benefits become even more profound.

Better Tasting Food

You can use reverse osmosis water in your cooking, such as for boiling vegetables and making gravy, sauces, and stock. Without the tastes of chemicals, metals, and other impurities in your tap water, you’ll be able to focus on enjoying the flavors of your food.

👎 Cons of Reverse Osmosis

There are several disadvantages of reverse osmosis that are important to know before you buy one of these systems.

Wastes Water

No matter what type of reverse osmosis water filtration system you buy, it will waste some water. There’s no way to prevent water waste in the RO filtration process, although some reverse osmosis water filters are more efficient than others. This is one of the biggest disadvantages of RO technology.

The traditional RO system wastes 4 gallons of water for every 1 gallon of filtered water produced. Thankfully, the RO water filters of today are a lot more efficient. You can find filter systems that only waste 1 gallon of water for every 1 gallon of filtered water produced, and even systems that waste 1 gallon of water for every 2 or 3 gallons of filtered water produced.

Removes Healthy Minerals

Another of the biggest disadvantages of reverse osmosis is that the process removes beneficial minerals from drinking water. Minerals like calcium and magnesium give water a pleasant alkaline taste, and an RO system removes these minerals along with the other impurities in water.

Some RO water filters offer additional remineralization filters, but with an extra filter replacement, the unit will cost more money in maintenance, and the filtration process takes slightly longer. You might not want to drink more water if you don’t enjoy the “flat” flavor of RO water.

Slower Filtration Process

Because of the multiple filter stages involved in an RO system, you won’t get immediate access to clean tap water. Some reverse osmosis water filters have a storage tank that reduces this issue somewhat, because clean water can be delivered from the tank when you turn on the faucet. However, tank-based systems take up more space and increase the risk for secondary pollution from the storage container itself.

Tankless RO systems are becoming the more popular choice, but it’s worth keeping in mind that these units will take a few seconds to deliver contaminant-free, clean water compared to filtered water solutions with fewer filtration stages.

RO system diagram

Requires More Frequent Filter Cartridge Replacements

Compared to other filter systems, reverse osmosis units are multi-stage, and have more filter cartridges to change. Replacement carbon filters, sediment pre-filters, post-filters, and remineralization filters are needed, as well as replacement RO membranes.

Although maintenance isn’t frequent – you’ll need to change the filters every 6 months to 2 years, depending on the filter type – the overall cost of cartridge replacements will be higher than paying for a single filter to be replaced in another system. If you want to save money on a filtration solution, the cost-related disadvantages of reverse osmosis will make it more difficult to do so.

May Require Electricity

Some reverse osmosis systems, such as countertop RO filters, require electricity to operate. Because these systems can’t use water pressure from your household water supply to filter water, they use electricity to generate the force required to send water through the system.

Not all RO units require electricity, so if you’d prefer not to pay extra for the costs of running your water filter with power, make sure you find a system that runs electricity-free.

Clogging

The tiny pores in a reverse osmosis membrane become easily clogged by an excess of certain impurities, like chlorine, iron, and hardness ions. The poorer your household water quality, the more quickly the membrane will become clogged. You’ll need to prioritize installation of a pre-filtering stage before the RO filter to prevent a buildup of mineral ions from shortening the lifespan of the filter.

Clogging can have a big effect on water pressure and flow, and has several disadvantages, including a reduced amount of water passing through the system, and a larger amount of water being wasted.