How to Purify Water – 2021 Ultimate Guide

How to Purify Water - The definitive guide

Purifying water is the process of removing impurities from a water source, ideally leaving just the H2O particles themselves.

There are now more options than ever before when it comes to purifying water at home. While all methods remove contaminants, they don’t all result in completely pure water.

In this guide, I’ll be sharing the best ways to purify water, helping you to choose the most suitable option based on your budget and the contaminants you want to remove.

🚰 Water Purification Methods

Filtration

Filtration is a process in which contaminants are filtered out of a water source.

This involves water flowing through a filter cartridge. The filter media contains pores that are large enough to allow water to pass through, but too small for select contaminants to pass. These contaminants end up sticking to the media, and are removed from the water.

Filter cartridges can have pore sizes from small to minuscule. All filters have a micron size rating, and this rating is a good indication of what a filter can remove.

For instance, filters with a 5-20 micron rating have larger pores that are designed for removing sediment particles. Filters with a 1 micron rating, or even smaller, can remove much smaller contaminants, like chlorine, lead, pesticides and herbicides.

filtration for home use

Some water filters are intended to act as pre-filters before smaller-pore filters that aesthetically improve water quality. Finding a filter with the smallest pore size isn’t necessarily the best thing, as it may become so quickly clogged with contaminants that it needs to be replaced almost instantly.

One of the most common types of water filter is the carbon filter. This filter grabs onto select water contaminants in a process known as adsorption. Carbon filters can usually be found in water filter pitchers, under-sink filters, refrigerator filters, and more.

Eventually, a filter will become so clogged with contaminants that it will stop filtering water effectively, and will need to be replaced. Though filter lifespan varies from one filter to another, the average filter lifespan is 6 months. Some filters can last for up to 2 years, while some may need replacing after as little as 3 months.

Contaminants Removed by Water Filters:

Most water filters can remove pesticides, herbicides, chlorine, lead, volatile organic compounds (VOCs), and mercury. Some can also remove fluoride and disease-carrying pathogens.

πŸ‘ Pros:

  • Can choose the most suitable pore size to target select contaminants
  • Budget-friendly options
  • Easy to use

πŸ‘Ž Cons:

  • Filters need replacing frequently
  • Not ideal for removing smaller contaminants, like bacteria

Distillation

Distillation involves boiling water until it evaporates, then condensing it into a clean container.

A countertop distiller consists of a boiling chamber, a condensing corridor and a separate glass container. Water is added to the boiling chamber and heated to a rolling boil. It then evaporates and enters the condensing chamber, where it is cooled, and drips out of the spout into the container.

Most contaminants have lower boiling points than water. This means that when water evaporates, the contaminants are left behind in the boiling chamber. The contaminants can then be washed out of the chamber during cleaning after use.

The Distillation Process

Some distillers have an optional carbon filter at the spout, which removes the few contaminants that are able to evaporate and condense with water.

To operate, a distiller needs to be plugged into a power source. While you won’t notice a spike in your energy bills from using a distiller, you will need to keep it on for hours at a time. It can take up to 5 hours for a distiller to produce a single batch of water.

Distillers are very low-maintenance to own. They don’t require any care except for cleaning, and changing the carbon filters, if you choose to use them. This also makes them very cheap to operate.

Contaminants Removed by Distillation:

When they boil the water, distillers are effective in removing hardness, inorganic compounds like nitrate and heavy metals, chemicals, and much more. The water boiling process is also effective in killing pathogens like bacteria.

πŸ‘ Pros:

  • Low-cost to maintain
  • Portable purification option
  • Easy to set up

πŸ‘Ž Cons:

  • Distillation process takes hours
  • Distilled water tastes “flat”, no mineral content

Ultraviolet Light (UV) Treatment

Ultraviolet light treatment, or UV treatment for short, is a water purification process that treats water contaminated with microbiological impurities, like bacteria, viruses, cysts and protozoa.

A UV system consists of the UV lamp itself and a sleeve or chamber, which the lamp sits in. Water flows through the chamber and is exposed to the lamp, which produces ultraviolet rays that damage the DNA of microorganisms, killing them and making them inactive.

UV Light Media

While microorganisms are still technically present in your water after using UV purification, they are unable to reproduce or make you sick if you drink them.

Most UV systems are used in conjunction with other systems, like whole home water filters or reverse osmosis filters, to offer a broader contaminant removal solution. However, they can be used on their own too – it just depends on whether you’re looking to solely eliminate pathogens, or you’d also like to address contaminants like chemicals and heavy metals.

A UV lamp typically needs to be installed at a cold water line, intercepting water as it flows towards your faucet. You may want to install a UV lamp at your home’s point of entry to provide purified water to your faucets, showers and appliances. Alternatively, if you just want to ensure that your drinking water is microorganism-free, you can install a UV filter beneath your kitchen sink.

Contaminants Removed by Ultraviolet Treatment:

UV purification systems kill types of bacteria and viruses, protozoa and cysts, including Giardia lamblia cysts and Cryptosporidium oocysts.

πŸ‘ Pros:

  • Failsafe treatment for killing microorganisms
  • UV lamps have long lifespan
  • Relatively easy to install

πŸ‘Ž Cons:

  • Doesn’t remove chemicals or heavy metals
  • Can’t be used if water is cloudy

Chlorination

Chlorination involves treating water with chlorine, which is a disinfectant that can kill microbiological contaminants like viruses, bacteria and protozoa.

Most public water supplies are disinfected with chlorine or chloramine (a chlorine by-product), making water safe to drink before it is sent to our homes.

Public water chlorination

Many well owners also use chlorination systems to kill bacteria in water before drinking. These systems inject a measured amount of chlorine into water, which is then stored in a tank to allow the chlorine to take effect.

Once water is chlorinated, it is sent into the home, ensuring that water is safe to drink, cook with, shower in, and so on.

Again, chlorination may be used in conjunction with other water treatments, such as well water filtration, to remove additional contaminants such as heavy metals. Chlorination is solely intended for killing bacteria, viruses, cysts and protozoa.

Contaminants Removed by Chlorination:

Chlorine acts as a disinfectant, and you can remove bacteria, viruses and protozoans from water with chlorination.

πŸ‘ Pros:

  • Chlorination systems provide whole-home solution
  • Easy to maintain – no filter changes etc.
  • Protects against recontamination

πŸ‘Ž Cons:

  • Adds chemicals to water
  • Only kills microbiological contaminants

Iodine or Bleach

If you’re looking for an affordable, immediate emergency purification solution, bleach is worth considering. It’s important to follow instructions carefully when purifying your water with bleach, as it’s a chemical that’s dangerous in large quantities.

Water bleaching

You should make sure to use unscented, soap-free chlorinated bleach for water purification. Here’s how much bleach you should add to a contaminated water supply:

  • For bleach containing 4 to 6% chlorine, like most household bleaches, add no more than 8 drops of bleach to a single gallon of water.
  • For bleach with 7 to 10% chlorine, add up to 4 drops of bleach to every gallon of contaminated water.
  • For bleach with 1% chlorine, add no more than 40 drops of bleach per gallon of contaminated water.

Once you have added bleach to your water, leave the water to sit for at least 30 minutes before drinking. This will give the chlorine enough time to disinfect your water. You should notice a slight chlorine odor in your water, which is a good sign – and if you can’t smell the chlorine, you might want to repeat the process.

Iodine can also be used to purify drinking water. For treating clear water sources, add 5 drops of iodine per quart of water. For cloudy water, add 10 drops of iodine per quart.

Iodine water treatment

Contaminants Removed by Iodine or Bleach:

Again, iodine and bleach disinfect water, killing pathogens such as bacteria, viruses and protozoans.

πŸ‘ Pros:

  • Affordable method
  • Bleach is widely available
  • Ideal for emergency scenarios

πŸ‘Ž Cons:

  • More dangerous than using purification/filtration systems
  • Requires accurate measuring

Purification Tablets

Water purification tablets are a popular choice for on-the-go water disinfection, especially for hiking and camping use. These tablets are portable and easy to use. Usually, one tablet can purify 1-2 liters of water within 30 minutes.

Purification tablets release free chlorine, chlorine dioxide or iodine into the water, which kills microorganisms like bacteria. They’re convenient, and, because the chlorine or iodine is pre-portioned, you know they’re safe to use if you follow the instructions on the packet.

You can use purifying tablets on any outdoor water supply, including lakes, rivers, and streams. However, while these tablets can clean water and make it safe for drinking, they won’t remove contaminants such as heavy metals and chemicals.

Purification tablet

Contaminants Removed by Purification Tablets:

Purifying tablets work as disinfectants, killing pathogens like bacteria, protozoa, and viruses.

πŸ‘ Pros:

  • Convenient for hiking, camping etc.
  • Affordable option
  • Quick to work

πŸ‘Ž Cons:

  • Add chemicals to water
  • Don’t remove metals or chemical contaminants

Boiling

Boiling a source of water is one of the simplest and most affordable means of water purification. To boil the water you plan to drink, bring it to a boil and let it sit at a rolling boil for at least 1 minute. If you live in an area of high altitude, you should boil your water for 3 minutes.

boiling water

Boiling your water will kill pathogens such as bacteria and viruses, and can also dissolve chlorine. However, it won’t remove any other contaminants – and, in fact, it may increase the concentration of contaminants per gallon of water, as some water may evaporate during boiling.

After boiling your water, you should leave it covered to cool before you drink it.

Contaminants Removed by Boiling Water

Boiling your water kills bacteria, viruses and protozoa.

πŸ‘ Pros:

  • One of the easier methods
  • Can be used to purify gallons of water at a time
  • Very affordable method

πŸ‘Ž Cons:

  • Requires a heat source
  • Must wait for water to cool before drinking

SODIS (Solar Purification)

Solar purification is an inexpensive water purification method that’s commonly used when boiling water isn’t an option. Solar disinfection doesn’t use direct heat – instead, it uses the heat from the sun to treat the water for drinking.

Solar Purification (SODIS)
Source: Wikipedia

To purify water with solar purification, you’ll need clear plastic bottles, a water supply, and direct sunlight. Fill the bottles with water until they’re around 3/4 full and place them in a sunny area. Shake for around 30 seconds, then add the last quarter of water and tightly close the lid. Leave the bottled water to sit in the sun for a minimum of 8 hours before drinking.

Contaminants Removed by SODIS:

Solar purification can kill bacteria, viruses and protozoa.

πŸ‘ Pros:

  • Easiest method on this list
  • Cheap- just need plastic water bottles
  • Can use water from any source

πŸ‘Ž Cons:

  • Water must be left for at least 2-8 hours
  • Can only be used when there is sunlight

πŸ‘ What’s the Best Way to Purify Water?

The best means of water purification depends on the contaminants you want to remove. There are many ways to purify water, and not all of them may be suitable for you.

I’ve listed the best water purification options for different circumstances below:

How to Purify Tap Water at Home

To purify tap water at home, you have several water treatment units to choose from. It’s worth considering whether you need a water filter purely for treating drinking water, or you’re looking to filter the water supplied to your whole house.

whole house water treatment system at home

Point of use filters, such as under-sink filters and countertop filters, are the most popular water purification method for filtering drinking water.

Here are some of the systems that can purify tap water at home:

System TypeAverage Cost
Water filter pitchers$10-$50
Reverse osmosis filters$50-$200
Under-sink water filter units$300-$600+
Distillers$100-$300+
Faucet water filters$50
UV light systems$500 – $1,000+

How to Purify Water in the Wild

You don’t have to boil your water in the wild to make it safe for drinking nowadays. There are plenty of portable water purification systems that you can take with you on hikes and camping trips for access to clean water during your travels.

Sawyer portable water filter

Some of the methods of emergency water filtration in the wild are:

Filter TypeAverage Cost
Straw water filters$30-$70
Water filter bottles$30-$70
Hanging gravity water filters$40 – $100

How to Purify Water Naturally

There are several methods of natural water disinfection for survival and emergency scenarios. If you don’t have access to filtered water, and you haven’t got a portable water filter for emergency use, you can still purify your water using natural methods.

Two of the best methods for naturally purifying water are:

  • Boiling your water – just need a heat source, a pot, and a storage container
  • Solar disinfection – requires just a water bottle and the sun

πŸ€” Frequently Asked Questions

Which impurities do I need to remove from my water?

It depends on your source of water. If you have city water, it’s highly unlikely that it’ll contain pathogens, unless you’ve been issued a boil water notice or you’re facing a survival scenario. But there will most likely be chemical and metal impurities that need to be removed, which will improve water quality and taste.

If you’re getting your water from a river, lake, or even a private well, your priority is to remove parasites and pathogens. If you’re looking for a full-time purification solution and not just a temporary survival method, you may want to combine several filtration systems, such as a UV lamp and an under-sink carbon filter.

Can water purifiers soften water?

It depends on the means of water purification you opt for. Most water filters are designed to filter water, not soften it. However, reverse osmosis filters can purify water and remove hardness minerals.

Water softeners are best for softening water, but they can’t be used to purify it. I recommend purchasing both a water softener and a water purifier if you’re looking for soft, clean water.

How can I find out what my water contains?

The easiest way to find out what your water contains is to get it tested. You can test your water using an at-home testing kit, which will give you an idea of what your water contains. You may prefer to get your water tested by a private laboratory, which can give you a more in-depth breakdown of the problem contaminants in your water.

If you drink city water, I recommend testing for chlorine, lead, pesticides, herbicides, chlorine and hardness. If you get your water from a private well, you’re best testing for coliform bacteria, hardness and more.