How Does a Whole House Water Filter Work?

Learn how whole house filters work in multiple phases to remove contaminants and provide healthy, great-tasting water from every faucet in your home.

By: Alyssa Scavetta

Life is all about enjoying the little things: putting the collar on your dog before a long walk; fresh linens on the bed before you sleep; the smell of sunscreen before your day at the beach. But notice that you can’t enjoy those moments without ensuring a little added protection before they happen. The same goes for enjoying clean, healthy water.

Before you determine whether or not a whole house filter is right for you and your family (or which whole house filter, for that matter), you’ll need to learn the basics about how it works.

What is a whole house water filter?

A whole house water filter is a system that is installed at the main water line of a home to provide filtered water throughout the entire house, including every faucet, shower, and appliance that connects to pipes like a washer. These systems are “point of entry (POE)” filters, because they remove contaminants at the point that water enters your home.

What does a whole house water filter do?

A whole house water filter provides clean water for the entire home — not just your kitchen faucet. This includes when you shower or bathe, when you brush your teeth in the morning, when you wash your vegetables before cooking, or when you refill your pet’s water bowl.. In essence, the water filter becomes a safeguard for all of the faucets, showerheads, and water-connected appliances in your house. These systems work to prevent contaminated water from entering the home for all of the uses we mentioned above, and more. That being said, how it actually works is fairly simple.

How do whole house filters work?

Most whole house water filters clean your water via a three-step process. First, a sediment pre-filter removes larger particles, then copper-zinc (KDF) and activated carbon filter treats the water, and finally the post-filter further polishes the water.

Step 1: The Pre-Filter process

Water entering the home is put through a pre-filter to remove larger particulates, impurities, and contaminants in your tap water. This step traps anything that is about five microns in size (anything larger than a red blood cell) — like sediment and silt. The pre-filter works like a sponge to continuously catch rust, dirt, and other particles. 

As we’ve mentioned in previous articles, most pre-filter cartridges should be replaced every two months depending on your water quality and sediment levels. When you first install your pre-filter, notice the material starts out white. Once you see a change in the filter color or you notice that your flow rate slows down, it’s time to change your filter.

Step 2: Copper-Zinc & Activated Carbon filter

Municipal water companies use harsh chemicals like chlorine and chloramines to treat your water before they send it to your home. Unfortunately, these contaminants can linger in tap water after treatment, and be present in the water you use for drinking, cleaning, and bathing. In fact, the contaminants can even evaporate in shower steam, contaminating the air you breathe. Activated carbon reduces chlorine (catalytic carbon is used to reduce chloramines) — besides improving air quality, removing these contaminants have multiple benefits for your well-being.

"This step traps anything that is about five microns in size (anything larger than a red blood cell)"

Copper-zinc (KDF) is also used to aid in the reduction of chlorine and to inhibit the growth of algae and bacteria in the tank. 

Activated carbon is also the most popular water filtration media on the market. It’s essentially made up of organic material with high carbon content (like wood, coal, or coconut shells). When it’s heated up (in such a way that it doesn’t burn), it results in char. That char is then treated to create a porous material that binds to impurities, pulling them out of the water. Moreover, the Activated carbon method comes recommended by the Environmental Protection Agency (EPA) to give you that extra layer of protection from a wide variety of contaminants that might still be present in your water supply.

Step 3: Your post-filter finishes the filtration process

While your post-filter is the smallest part of the process, it’s mighty. Post-filters use robust, layered mesh screens to further improve water quality. It essentially acts as a polishing agent, catching any remaining sediment and organic particles that might still be in your water. Just be sure to replace your post-filter every six months — that will keep your system unclogged so you don’t experience pressure drop.



High-performance water filtration system reduces chlorine and more from every tap for 1,000,000 gallons or 10 years.

Extra filtration options for whole house systems

Additionally, you can pair your whole house system with an ultraviolet (UV) light. This added system sterilizes bacteria, viruses, and cysts to safeguard your drinking water. These types of filters are recommended for homes using well water

Furthermore, if your home is supplied with hard water, we suggest using a salt-free water conditioner. Otherwise known as a water descaler, these devices deter minerals from binding to form scale that can damage pipes and appliances and cause spotting on dishes and bathtubs.

See how whole house filters work firsthand

The best thing you can do for your family is to protect them from contaminants before they enter your home, so you can drink, cook, and bathe with peace of mind. A whole house filter can do just that, and you can customize your whole house system to match your specific needs. Visit our online store today to find the perfect filter for you and your family!