Common Types of Water Filters and How They Work

Would a filter at the faucet is enough to bring you safe water, or should you install a water filtration system for the whole house? Would activated carbon filter work, or is UV treatment a better option? It’s difficult to find an exact answer.

There are many factors that may influence the method of filtration and type of water filter you use in your home. Things to take into consideration include the biochemical properties of the water, water pressure, the material and specs of the pipe, and your budget, among other things. All of those differ from household to household.

This article aims at introducing to you the most common types of residential water filters. Following that is the popular methods used in water filtration and purification. We'll also discuss the pros and cons of each type so you'll have a better idea of what would be best for your home.

How Water Filters work: Popular Methods of Filtration

Each method has its own advantages and disadvantages. Most of the time, a water filtration system is a combination of two or more methods and materials.

1. Activated Alumina

Activated alumina is made of aluminum oxide (Al2O3), the same substance as sapphire and ruby without the coloring impurities.

The material is effective in removing fluoride, arsenic, and selenium from drinking water. With many pores on its surface, alumina can reduce up to 99% of fluoride concentrations in the normal fluoridated water.

• Highly effective in removal of fluoride, arsenic, and selenium

• Cost-effective

• Possible leaching of aluminum to the water, depending on the pH level and the composition of the treated water.

2. Activated Carbon

Activated carbon, or activated charcoal, is a form of carbon that has been processed to maximize the number of pores on them. When water flows through an activated carbon filter, its pores trap the pollutant molecules inside.

Activated carbon has a large adsorption surface. The material is widely employed in water treatment to remove organic compounds or extracting chlorine from water. It can be the only medium in a pitcher, or serve as a pre- and/or post filter in under-sink and whole-house filtration systems.

• Effective in removing chlorine, sediment, volatile organic compounds (VOCs) and improving the taste and the smell of the treated water.

• Inexpensive

• Does not require electricity to work

• Cannot remove minerals, salts, and dissolved inorganic compounds.

3. Ceramic Filters

Ceramic is a material with a lot of tiny pores on it. As water runs through the filter, these pores keeps outside anything larger than the their sizes.

Ceramic water filters are sometimes treated with silver to kill bacteria and prevent mold and algae in the water.

• Inexpensive, last for years

• Doesn’t require electricity

• Effective in reducing bacteria and protozoa

• Simple to set up and use

• Not effective against viruses

• Slow

4. Reverse Osmosis

Reverse osmosis is a method of water filtering in which water is forced through a membrane with small pores. These pores allow water to run through, but keep the contaminants outside, which afterward are flushed away.

Coming with pre-filters, post-filters, and reverse osmosis membranes, RO filter systems tend to cost more than other types of filter. It's rare to see them in whole-house filtration systems.

However, thanks to their high effectiveness in removing heavy metals and various harmful chemicals, they are a favorable choice among health-conscious households for under-sink and countertop filters.

• Highly effective in removing pollutants, parasites and viruses

• Doesn’t require electricity

• Waste of water (only ⅓ to ¼ of the water is purified, the rest is wasted)

• Requires high water pressure

5. Ultraviolet Light

UV water purifying systems use light of a high frequency to irradiate water through a glass element. As water passes through the element, the light inactivates and kills living microorganisms by damaging their cellular function.

UV light is one of the safest and most effective ways to treat virus, bacteria, and protozoa in water. That being said, it has its weaknesses: non-organic contaminants can obstruct the light, deeming it ineffective. The light may fail to deliver the desired results when working on water with high concentrations of sediments and pollutants.

For this reason, UV lamps rarely stand alone as a purifier. It works best as the final stage in a system to treat microorganisms in water that's been filtered and has become clean and clear.

• Kills parasites, bacterias, and viruses

• Expensive

• Needs energy to operate

• Doesn’t remove non-living contaminants (minerals or fluoride)

6. Distillation

Distillation is a process of water purification with very high efficiency. During this process, water is boiled into steam, which is then cooled down to the form of liquid and is collected in a clean container.

In the household scale, we usually employ this water treatment method in countertop distillers to make drinking water for small families.

• Removes most contaminants. Kills bacteria.

• Improves taste and smell of the treated water

• No replacement needed

• Very slow. Takes long hours to produce a small amount of pure water.

• Requires electricity to work

Types of Water filters and Purifiers for Residential Use

The most frequently seen water filters in American homes.

1. Water Filter Pitcher

Thanks to their low cost and portability, water filter pitchers are among the most common types of water filters used in households.

A typical water filter pitcher has two parts. At the center of the upper half is a filter filled mostly with activated carbon, where you will pour water in to be treated. The filtered water will drop down to the lower part of the container, and you can pour it out for use from there.

Due to their limited capacity, water filter pitchers are mainly used to purify tap water for drinking and cooking. They’re also a safe and convenient way to get clean water when you’re outdoors, on a camping trip for example.

• Low cost

• Can remove lots of chemicals and minerals in water

• Portable

• Easy to use

• Slow. Confined capacity – you need to pour water in and wait for it to work.

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2. Faucet Water Filter

As its name suggests, this is a small device you install right on your faucet. It removes the contaminants in the water right before it comes out, leaving you with fresh water for cooking and washing.

Faucet water filters are generally inexpensive, making them a popular choice in the households. They’re best at improving the smell and the taste of tap water in areas where the water is relatively already safe and clean.

• Small, inexpensive

• Convenient, no need to constantly fill water

• Easy to install

• Slows the flow down significantly

• May not work with low faucet

3. Showerhead Filter

Similar to faucet filter, this is a device you install on your shower head to filter the water for your shower. Sometimes, the filter comes with a shower head itself.

Filters for shower head are advised for areas where the water contains a rich amount of chlorine and fluoride, which are known to cause dryness and irritations to individuals with sensitive skin. Many users reported they feel reduced hair loss and a smoother skin after the filter is installed in their bathroom.

• Removes simple contaminants, improves hair and skin

• Inexpensive

• Easy to install

• Slow flow

4. Countertop Water Filter

Countertop water filters are a slightly better choice when you want to purify your tap water without having to keep filling and emptying a jug. They are small devices connected to the faucet, purifying water as you turn the tap on. A countertop filter may sometimes come with its own faucet.

Most countertop filters have a small footprint. Still, they do take up some space on your countertop and are thus less favored at households with a narrow countertop.

• Fast. Filters water as you turn the tap on

• Middle-ranged price

• More filtration than faucet filter

• Takes countertop space

5. Under Sink Water Filter

An under-sink water filter is typically a water filtration system installed under the sink in your kitchen. It removes bacteria and pollutants, making the water safer to use.

Under-sink water filters are usually bulky, expensive, and are not very portable. However, they can process a larger amount of water at a much faster rate compared to faucet or countertop devices.

• Large, treat more water within a short time

• Usually hidden under the sink, not visible

• Can filter more different kinds of contaminants

• Expensive

• Difficult installation

6. Whole House Water Filter System

Whole house water filter systems are usually seen in households where tap water is not an option. They’re typically installed right at the water tank, connecting to the main pipe, purifying the water before it is distributed to different areas in the house.

• Filters water right at the main pipe. No need to find filters for different taps/sources in the house

• Large system effectively removes various contaminants

• Saves money on clean water in long term

• Expensive

• Needs professional installation

What kind of water filtration are you using in your home? Does it improve the smell and the taste of your water? Share your experience with us.