How does a water filter work?

Using contaminated water is the source of several diseases. Whether you have contaminated water for drinking water or for tap water, you must take all measures to install a highly efficient water filtration system to remove larger particles and other contaminants that are invisible to the naked eye.

In this article, we will look at briefly how water filters work and the best house filtration systems in the market. Finding the ideal water filter system; be it a whole house filtration system or a water filter pitcher, we are here to make the search simple for you. Let us get started to learn how to keep away contaminated water with the help of water filters.

How does water filtration work step by step?

All types of water carry some form of impurity in them. It is crucial to remove contaminants from water before consumption. The molecular nature of water makes it an excellent agent for dissolving things. Therefore, water is a magnet for dirt. Unfiltered water can be made into clean water, pure water, or distilled water by a water treatment process. Even your city water might have a special water treatment process to treat water to remove chemicals and to remove particles that are hazardous to health.

How does water filtration work step by step

The water filtration method for purifying water is of two basic types; Physical filtration and Chemical filtration. Between mechanical filtration or physical filtration systems and chemical filtration systems, there are many elaborations done to intensify the water purification process.

The mechanical filtration method will consist of a sieve, which could be any material (a very fine filter like a textile membrane or a thin gauze), to trap larger particles.

The second method is not just to trap chemical impurities or to remove chemicals, rather it is to remove contaminants as the water passes through an active material.

What are the four types of water filters?

When it comes to water filters and the water filtration system to carry out water purification there are several types to be discussed.

What are the four types of water filters

The popular ones among them are the water softener that is known to remove magnesium and calcium ions that are the major mineral contaminant in hard water, ultraviolet water filtration to remove microscopic bacteria, viruses, and other agents of contamination, sediment filters (a sediment filter will remove dirt, sand, clay, and even rust flecks from aging pipes), carbon filtration to remove chlorine, pesticides, and herbicides, etc.

Apart from this, the 4 main types of water filters are;

  1. Activated carbon filter
  2. Reverse osmosis filters
  3. Ion exchange
  4. Distillation

1. Activated carbon filtration systems

An activated carbon filter is a common type of water filtration system that is used to improve water quality. These water filter systems make use of activated carbon granules that are based on charcoal. The highly porous nature of activated carbon granules is equipped to trap chemical impurities by a process called adsorption.

Activated carbon filtration systems

Although activated carbon filtration is an excellent method to improve water quality by removing chemicals, it is not an ideal choice of water treatment for hard water. Hard water minerals like magnesium and calcium ions, sodium ions, microbes like bacteria, nitrates, fluorine, and other compounds cannot be removed efficiently by activated carbon filtration systems.

The other disadvantage of using activated carbon is the cost. Although they might always fit under the description of expensive filters, the repairs and replacements of these filters come with a considerable cost. Activated carbon filters can get clogged up with impurities. This can sometimes be an ongoing process.

2. Reverse osmosis systems

Tap water or any unfiltered water source can have a high supply of dissolved inorganic solids. The most common among these can be magnesium and calcium ions. Getting clean water or filtered water with reverse osmosis filters is the process of forcing this contaminated water through a semi-permeable membrane under a certain amount of water pressure. As the water passes via the membrane, the contaminants in the water, including magnesium and calcium ions will be retained.

Reverse osmosis systems

Reverse osmosis systems are highly advanced methods to clean water and remove particles that contaminate it. Another feature that you might notice with reverse osmosis filters is that they work in combination with others, making the best use of how other water filters work. The sediment filters or mechanical filtration systems and absorption or activated carbon water filters are the different water filter systems that reverse osmosis filters work with. The water flow will be directed into these filtration systems as well.

Although the fact that reverse osmosis water filters work with water pressure and not electricity to ensure the water passes through the semi-permeable membrane, the minor setback with reverse osmosis filters is the waste-water. There is a certain amount of waste-water produced that has to be discarded to the drain, preferably the kitchen sink.

Since reverse osmosis is a water filtration system that uses multiple filtration techniques, it does fall under expensive filters. However, the cost is definitely worth the effort to purify the water supply. The water quality is enhanced to give clean water that is ideal for consumption.

3. Ion exchange 

Ion exchange is more of a water filtration method that acts as a water softener for hard water. Simply put, ion exchange is a process where bad ions are exchanged for good ions. During ion exchange, the atoms of the hard water are split and they are exchanged for certain ions that are less troublesome.

Ion exchange 

Here is the process in brief; the ion exchange water filters work by exchanging the magnesium and calcium ions that are present in hard water, with the sodium ions in the zeolite beads that ion exchange filters are built with. These water filters work by replacing the incoming calcium and magnesium ions with sodium ions.

The end product of the ion exchange filtration system is not our water. The sodium ions that are added are also a contaminant, that can potentially become hazardous for people on a low-sodium diet. Ion exchange can also be disadvantageous when it comes to maintenance. Replacement recharge water filters are required to supplement the replenished sodium ions.

4. Distillation

The easiest method to get pure water is by boiling it. Water has a low boiling point and therefore it is easy to kill several types of bacteria by simply boiling water. Although the heat is sufficient to kill bacteria, it is not sufficient to get rid of chemicals, limescale, and contaminants of this nature.


An advanced and by far the best method for purifying water is distillation. To get distilled water; the contaminated water is boiled and the steam that results from the boiling process is captured and cooled down or condensed back into the water in a container separately.

Distilled water is free from heavy metals. Hard water treatment with distillation is the best form of water filtration system. This is because most of the heavy metals present in hard water boil at a temperature higher than water. Therefore, these heavy metals from hard water can be retained as the steam is separated and boiled away.

You must remember that distillation and distilled water are not free from volatile organic compounds. VOCs or volatile organic compounds boil at temperatures lower than the boiling point of water. Therefore, these contaminants will evaporate and distillation is not a successful method to remove them.

What is the healthiest way to filter water?

The healthiest and easiest filtration system is boiling. Boiling water over a stove top has been the most trusted water filtration system for years together. Boiling tap water or drinking water supply before consumption is sufficient to remove various types of harmful disease-causing bacteria.

What is the healthiest way to filter water

However, even boiling is not completely safe to remove all contaminants. Reverse osmosis or a trusted water purifier can be relied upon to obtain the healthiest water to purify the water supply. These water filtration systems are built with multiple advanced water filters that will purify water effectively.

How to choose a suitable filter for you?

Choosing the right house filtration system for any home is important. Investing in the water filtration system must be done after careful analysis of various factors that surround filtering the water supply. Here are some free factors that you must look at before you purchase house filtration systems.

How to choose a suitable filter for you

Compatibility of the water filters with the water supply or water source at home. The water filter must be compatible with the kitchen sink, plumbing, faucet, and other outlets of the water supply.

The cost of the after filters, installation, repairs, maintenance, and replacement.

The purpose of filtering water will also determine the water filters to be used. For example; reverse osmosis filters are the best to filter water for cooking and drinking, water softeners for hard water, and activated carbon water filters to remove VOCs.

What is the best water filter?

The best water filter available is the Waterdrop- 10UA Water Filter System. This is the best water filter system that one can invest in for residential and commercial use. This WQA-certified filter system from Waterdrop has all the necessary features to purify water. Its innovative design and long lifespan make it a worthy investment.

The push-to-connect fittings of this water filter make it simple and effortless to be installed. The twist-and-lock design takes only a couple of seconds to install. The filter comes with a 3/8″ hose with a direct connection. By using a 3/8″–1/2″ convertor fitting this water filter system can be connected to both 1/2″ and 3/8″ cold water lines and faucets.

The Waterdrop- 10UA Water Filter System is also designed to be compatible with multiple water filters when it’s time for a replacement. This makes maintenance and repairs easy. It is also one of the best water filters that can be installed anywhere effortlessly; be it in a kitchen, RV, office, etc. Meeting your everyday water needs can be made simple with this filtration system.

Frequently Asked Questions:

1. What do water filters not remove?

A water filter cannot remove bacteria, lead, fluoride, and other such agents. You must use a reverse osmosis system or distillation process to remove these contaminants and others that cannot be removed by water filters.

2. How does a homemade water filter work?

A homemade water filter can be made using filters like gravel or stone, sand, and activated charcoal. The top layer of stones and gravel is effective to remove leaves, insects, or larger contaminants. The sand layer will be able to remove finer impurities and the final layer of activated charcoal to remove contaminants via chemical absorption.

3. How does a UV water filter work?

Water filters with UV rays are used to kill water-borne microorganisms. You can keep the water completely free from water borene pathogens by treating it with UV water filters. They will also prevent the reproduction of these microorganisms by disrupting their DNA. An added benefit of UV water filters is that they do not contribute to any chemical changes in the water.

4. How does the zero water filter work?

A ZeroWater filter is designed to remove all dissolved substances from water. These water filters will ensure that there is nothing left in this drinking water.

5. How does a refrigerator water filter work?

Refrigerator water filters use chemical reactions between activated carbon and chlorine in the water. The activated carbon will behave like a sponge. It is not just capable of neutralizing the chemicals, pesticides, and herbicides in the water, but it can also absorb the chemicals and other contaminants in the water.

6. What is the best water filter pitcher?

The best water filter pitcher that you can find in the market is the Brita Tap Water Filter Pitcher. This convenient-to-use water pitcher can hold 6 cups of water and is of the right size to fit into any refrigerator. This Brita pitcher can effectively reduce 99% lead, Chlorine (taste and odor), Cadmium, Mercury, Benzene, Asbestos, and more.

Being a user-friendly filter, with electronic indicators for filter reminders, making the best use of the Brita pitcher can help you to replace up to 1,800 16.9 fl oz single-use plastic water bottles a year.


With this, we have reached the end of the article. We trust you were able to learn the process of how a water filter works and the best filters for you to rely on. Remember to carefully select the water filter that you invest in and to consume only filtered water to avoid several kinds of waterborne diseases.

About The Author

Our Web Producer

Judith— a passionate water treatment specialist — is a waste water management enthusiast, clean drinking water advocate, and someone with deep personal experience and knowledge about various water equipments. Her work was mentioned in countless notable water associations. Previously she was an editor at Water Alliance.