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The Lazy Man's Guide to Water Filtration vs. Water Purification

by Dr. Jonathan Doyle | Updated Feb 25, 2021

Do you know that an average home uses about 80-100 gallons of water per day to accomplish indoor tasks, such as taking showers and flushing the toilet? However, 29% of the world's population lives off contaminated water. Such water causes more deaths in a year than wars and violent crimes combined. Every two minutes, a child dies of a disease caused by ingesting unclean water.

What the numbers above show is that freshwater is vital for the health and wellbeing of humans. Thus, homeowners who get their water from different sources often choose a water filtration or purification system. Even though these two systems may seem interchangeable, they are different in several fundamental ways.

This article will show the difference between water filtration and purification. It looks at different water purification methods, such as boiling, distillation, chlorination, and filtration. We also present various filtration methods, such as sediment filtration, reverse osmosis, and ultrafiltration.

Importance of Water Purification and Filtration

Without water, there would be no life. For instance, our bodies are 60% water. Water is involved in several vital body functions like transmitting essential nutrients and vitamins, flushing out toxins, regulating temperature, and lubricating the joints. It also ensures that organs of the body, such as the skin, retain their shape.

Vital as it is for humans, some of the available water is not safe for human consumption. It comes with contaminants. These are foreign elements present in water that adversely impact its viability for human and animal consumption. Water contaminants may be naturally-occurring or human-made – these include chemicals, debris, bacteria, viruses, radioactive substances, and so on.

Defining Water Purification and Water Filtration

With the contaminants in the water, it becomes crucial to either purify or filter the water. Before we go deeper into water purification and filtration, we need to start by defining the two processes to clear the difference between them. Even though the two processes may be different, they serve the same purpose: to make water clean and safe to consume.

Water Filtration

The process of reducing or getting rid of solid contaminants in the water is known as filtration. The idea behind the filtration process is that the particles of some of the contaminants are bigger than those of water. Therefore, creating a semipermeable membrane would allow the desirable water particles to pass while preventing the larger undesirable particles.

It is important to note that the dissolved particles in the water, which are smaller or the same size as the water particles, will pass through the semipermeable membrane. This implies that the filtration process alone may not be able to get rid of all the impurities. This is why modern water filtration systems have been made sophisticated enough to ensure that as few impurities as possible can pass through the semipermeable membrane.

Water Purification

For water to be safe to drink and meet other standards imposed by authorities, the concentration of suspended matter and impurities must be reduced. These impurities include parasites, fungi, bacteria, viruses, algae, and other unwanted biological or chemical contaminants. Water purification seeks to remove undesired chemical compounds, biological contaminants, and organic and inorganic materials using various methods. Water filtration is one of these methods.

Water Purification vs. Filtration: What’s the Difference?

From the definitions above, we can note that even though people use water filtration and water purification interchangeably, the two processes are different. Water filtration uses different methods to separate impurities from the water so that the water you eventually use does not have contaminants. It is a method of cleaning water by separating the impurities from the water using a filter.

On the other hand, water purification attempts to remove all the impurities removed by the filtration process while eliminating undesirable minerals from the water. This method is not restricted to using a filter to separate the impurities. It may also involve the use of chemicals or separating water particles from the impurities through chemical reactions.

Purification removes more impurities than filtration so that the water meets a given standard. However, advances in technology are making water filters more sophisticated. They are now able to clean the water to the standard achieved by purification.

The differences between filtration and purification can mainly be seen in the techniques that each uses. However, even though we refer to differences between water filtration and water purification, the technics are not mutually exclusive. This means that a purification method can also use some filtration techniques and vice-versa.

Water Purification vs. Filtration: What’s the Difference?

Over time, water filtration methods have been getting more accessible, sophisticated, and easier to use from anywhere. Below, we look at some of the standard methods of cleaning water through the process of filtration.

Sediment Filtration

Sediment filtration is a method used to separate solid particles from the water. It is the most popular home-based water filtration system. The sediment filtration material is called a sediment filter. It is usually made from polypropylene or pleated polyester with micron ratings that range from 1 to 100.

Activated Carbon

Carbon removes the contaminants in the water by chemically attaching to the water. Activated carbon filters come in different types. Some basic ones remove the chlorine from the water to improve taste and get rid of the odor. Others are more sophisticated and remove harmful contaminants found in the water, like metals. However, carbon filters do not remove organic pollutants in the water.

Reverse Osmosis

One of the most commonly used water filtration methods is reverse osmosis. In this method, water passes through a semipermeable membrane that allows the water to pass while preventing the impurities. Because this method offers the finest level of filtration, it is commonly used in environments like hospitals.

Usually, a reverse osmosis system is placed under the sink. Water coming from the main supply passes through the filter before it comes out of the tap. This method does not remove metals, solvents, and pesticides. Also, the fact that the water has to go through several stages can render the method more expensive.


The ultrafiltration (UF) method uses pressure to move a fluid through an extremely fine semipermeable membrane (in most cases, 0.01 to 0.5 microns). This makes the filter able to get rid of microscopic contaminants, such as bacteria and parasites. The main advantage of this method is that it retains essential minerals in the water.

The UF method's main disadvantage is that it cannot remove the solids dissolved in the water. This is why the method is often used in conjunction with other methods like reverse osmosis and activated carbon.

Water Purification Methods

There are several water purification methods, some of which share similarities with filtration methods:


Boiling is the cheapest and easiest way to purify water. The boiling process kills parasites, germs, and bacteria. Even though the general advice has been to let the water boil for up to five minutes, some recent studies show that just getting the water to boiling point is enough. The main advantage of boiling as a purifying water method is that it is inexpensive and can be done anywhere as long as you have a heat source. Also, boiled water can kill most microorganisms.

While boiling may be the only choice when there are no other means of purifying water, the method does not totally eliminate contaminants. For instance, it cannot eliminate the nitrates used in fertilizers that can enter the water system and other undesirable minerals like mercury and lead found in underground natural deposits.


Filtration involves physically separating water from contaminants. It is perhaps the most prevalent purification method, and water filters are easy to acquire at home.

The efficacy of a water filter depends on the size of its pores, measured in microns. The standard pore size of a good-enough filter is 0.2 microns. To set up a filtration system, charcoal and activated carbon are arranged in cylindrical or round blocks. As the water goes through the carbon, the contaminants and chemicals are absorbed by the carbon, allowing clean water to go through.

The filtration process removes impurities like metals, sediments, parasites, and bacteria. Filtration is a quick process and does not alter the taste of the water.


Distillation dates as far back as the time of the Ancient Greeks in AD 200. This is probably the most effective method of cleaning water because when water is turned into steam by boiling, the impurities are left behind.

The distillation process requires a heat source, containers for boiling the water and collecting the condensed steam, and a tube for the vapor to pass through. While the distilled water is free from contaminants, the distillation process may also destroy the water's essential minerals.


Chlorination is a method that has been used for over a century to disinfect water. This purification method removes viruses and bacteria. Because it kills undesirable microorganisms in water, this is a method that works well when combined with filtration.

For chlorine to be effective, it has to be in the water for some time before the water is used. Also, the dosages have to be managed, with lower dosages taking more time to clean the water. With regards to the safe levels of chlorine in drinking water, the Centers for Disease Control and Prevention advises that “chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm)) are considered safe in drinking water.”

Iodine Addition Iodine kills bacteria and viruses easily but may leave your water with an unpleasant taste. It is a powerful substance and should only be used sparingly. Iodine, used in carefully-measured quantities (two drops per quart of water) and allowed to stand for 30 minutes, is deadly to most biological water contaminants.

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