Types of Water Filters & What They Do

Got a water filter in your fridge? Great!

Water filters can make a huge difference when it comes to what your water tastes like and how clean it is. Here’s how they all work and what they can filter out of your water!

Why do you need a water filter?

There are plenty of reasons to use a water filter, and not all of them necessarily have to do with the cleanliness of the water.

Most of our drinking water comes from a public water system run by the city or county we live in. Regardless of where you live, all public water systems have to carefully monitor the water system and have an annual water quality report submitted to the Environmental Protection Agency (E.P.A.). The report — also known as a Consumer Confidence Report or a water quality report — provides both the E.P.A. and the public with valuable information on the water sources, the levels of regulated contaminants, any potential health effects and how your community’s water compares to water around the nation. 

Knowing what your local water system contains in terms of minerals or contaminants is a great first step in choosing a water filter that’s right for you. Each water source is different, so your water filtration needs will be different, too.

Most of the time, though, the water in your public water system is safe to drink as-is, and a common reason to use a water filter is to change the actual taste of the water, not necessarily just to scrub it clean. Because drinking water is often tapped from underground aquifers (or from rivers and lakes fed by underground aquifers) the minerals in the ground can greatly influence the taste of your water. It’s these minerals that you can filter out using water filters, while more complex contaminant cleaning is done by larger filtration machines. 

There are a few types of filtration systems out there that you might already know about:

• Water filter pitchers
• Refrigerator filters
• Faucet-mounted filters
• Faucet-integrated filters
• On-counter filters
• Under-sink filters
• Whole-house water treatment devices

Each of these systems is installed in different areas of the home, and each can use a variety of filtration methods to do the job. Ultimately, the system you use and filter it uses depends on what your community’s water supply looks like and what your building’s needs are. 

We’ll go over the different kinds of water filter technologies out there, but for the most part all you really need is a pitcher filter if you want to change the way your water tastes. It’s a great place to start!

Types of water filter technologies & how they work

Mechanical water filters

A sediment filter is a type of mechanical water filter, meaning it uses a mesh or porous material to physically remove particles from your water. The mesh has to be super fine in order to strain out any impurities — the finer the mesh, the more it can filter out!

The most common kinds of mechanical filters are made from ceramic or tightly-wound cotton thread, both of which have microscopic pores that allow water to pass through but trap dirt, rust, dust or certain bacteria. 

Activated carbon water filter

A carbon filter is a type of absorption filter, meaning it filters out contaminants by absorbing them into the larger, heavier carbon particles. The carbon is easier to filter out of the water due to its size, and it takes all the bad stuff with it!

Activated carbon filters can come in granular form or in a block form — either way, the large, rough surface area of carbon particles is perfect for catching and trapping contaminants.

Ion exchange water filter

Water sources rich in minerals like calcium and magnesium are typically referred-to as “hard water,” since the high levels of these minerals can cause limescale buildup in pipes and in appliances. Hard water might also have a slightly metallic taste, due to the mineral content. 

Ion exchange filters work as water softeners by breaking down the hard minerals, therefore “softening” the water’s contents. In this kind of filter, water passes through a system of resin beads that have been charged with negative sodium ions — the negatively-charged ions attract the positively-charged calcium and magnesium ions, removing them from the water passing through! 

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Reverse osmosis water filter

Reverse osmosis is the process by which water is filtered several times before being forced through a thin membrane, trapping a significant amount of contaminants while allowing fresh water to pass through to the other side. The only downside is that wastewater is a byproduct of reverse osmosis, and there’s not much to do with it other than discard it.

Ultrafiltration water filter

Ultrafiltration filters do exactly what it sounds like it does: use an ultrafine filter to remove contaminants!

The filter is fine enough to remove pretty much everything except dissolved minerals, making it almost as effective as a reverse osmosis filter. However, since there’s no wastewater created as a byproduct, there’s less waste and higher efficiency!

Ultraviolet water filter

The last kind of water filter we’ll talk about is an ultraviolet water filter, or UV filter. 

UV filters work in two steps. First, pieces of sediment are filtered out of the water using a sediment filter, after which waves of ultraviolet light pass through the water and kill any microorganisms living inside. This two-step process filters and purifies the water, and it’s especially useful with well-water systems that often contain higher amounts of bacteria. 

Whatever kind of water filter you use and whatever kind of pitcher is in your fridge, knowing how these water filters work can help you understand what’s happening to your water! 

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Featured photo by Irvin Zheng on Unsplash