What is a Whole House Water Filter and How Does It Work?

If your home’s drinking water supply is contaminated with chemicals, metals, and other impurities that affect its taste, smell, or appearance, there’s an obvious solution: a whole house water filter.

You might know that this type of water filter should, in theory, be able to solve your current water quality issues.

But exactly what is a whole house water filter? How do whole house water filters work?

What do they remove? And why do so many people use them?

We’ve answered all your pressing questions in this guide.

🚰 What is a Whole House Water Filter?

A whole house water filter is a water filter that’s installed on your main water line at your home’s point of entry, providing whole home filtration benefits.

Whole house water filter systems don’t only treat your drinking water. They ensure that all faucets and appliances in your home, from your showerhead to your washing machine, receive clean water.

There are a variety of whole home water filters available today. Each of these systems is designed to remove a different selection of impurities, such as iron, manganese, chlorine, sediment, and microorganisms.

If your water is damaging to your plumbing, poor-tasting, or unsuitable for drinking, a whole house system will solve your problems.

Related: We reviewed the best whole house water filtration systems of 2024 – read them here!

🧰 Where is a Whole House Water Filter Installed?

A whole house water filter is installed at your main waterline, or the pipe that brings water into your home.

The filtration system is installed upstream of your water heater. This means that you can benefit from hot and cold filtered water in your home.

Typically, whole home water filters are installed in basements, garages, cupboards, or sheltered outdoor locations. There should be enough space around the system to comfortably perform maintenance, such as water filter changes.

❔ How does a Whole House Water Filter Work?

So, how does a whole house water filter work?

It depends on the type of system you buy (more on that below).

The general goal of filtration is the same: to trap, block, reject, or adsorb impurities that are affecting your water quality.

Some water filter systems consist of a single filtration stage, using one type of filter media that can effectively target a specific problem. Other whole house filters use two or more stages of filtration and are designed to target a selection of contaminants, providing double, triple, or quadruple the benefits of a single-media system.

We’ve listed each of the three common stages of a whole home filter, and how they work, below.

Stage 1: Pre-Filtration

Nearly all whole house filters come with a pre-filter. The pre-filter is typically a sediment filter designed to remove large particles, like sediment, rust, sand, and silt, that could damage the filter media.

A pre-filter is especially important in homes with well water supplies, which are more likely to contain large water contaminants. But a sediment filter doesn’t only clean water – it also improves the performance of, and increases the lifespan of, the main filter stages that follow.

Pre-filtration prevents the main filter media from becoming quickly clogged. If your water filter could benefit from a pre-filter, it’ll likely come with one built in.

Stage 2: Main Water Treatment

The second stage is the key purpose of the water filter. The main water treatment stage uses media designed to target the contaminants that the filter is advertised to remove.

Activated carbon filters, sediment filters, KDF filters, reverse osmosis filters, air injection filters, and UV filters are all common second stages in whole home water filters.

Water softeners are also common. However, water softeners aren’t technically classed as water filters (see our guide on water softeners vs water filters to know the difference) because they soften, not filter, water.

We’ve shared more info about these main water treatment stages below.

Stage 3: Post-Filtration

Most whole home water filtration systems come with a post-filtration stage. A post filter usually gives water a final touchup before it travels back into your plumbing system.

A post filter might be a final activated carbon stage that further removes chlorine taste from water, or it might be a remineralization stage that adds healthy alkaline minerals into purified or acidic water, improving its taste and quality.

Post-filters can also remove remaining sediment from your water, preventing damage to your plumbing system.

🌀 What Are the Different Types of Whole Home Water Filters?

We’ve shared a full guide on all the different types of whole home water filters, so we won’t get into too much detail here.

But if you just want an overview of how some of the most common types of whole home filtration systems work, we’ve provided that below.

Carbon Filters

Carbon filters, usually activated carbon (but sometimes catalytic carbon) are the most popular water filters for whole home use.

Activated carbon is an effective filtration media that holds NSF certifications to remove a whole host of organic contaminants, including pesticides and herbicides.

Most activated carbon filters are designed to focus predominantly on the removal of chlorine, chloramine, and disinfection byproducts, improving water quality and indoor air quality.

The highly-porous carbon media adsorbs pollutants and chemicals as contaminated water travels through the pores, trapping the impurities and producing better-tasting water.

If water has a chloramine problem, catalytic carbon is more effective than activated carbon for removing this chemical.

Sediment Filters

Sediment filters work like sieves to trap contaminants larger than a certain micron size . These filters come in a range of different pore sizes, allowing you to target sediment particles within a certain size range. Filters are designed in sizes from 0.5 to 50 microns, sometimes higher.

Sediment filtration is often used as a pre-filtration stage, but you can buy standalone sediment filters if you need targeted sediment removal.

Most sediment filter cartridges last for 6-9 months.

KDF Filters

KDF, or kinetic degradation fluxion, uses high-purity zinc and copper media to remove a range of contaminants.

There are a number of different types of KDF media. Some are designed to be paired with other filters, like carbon-based media, to improve their performance and remove more contaminants. Others can be used as standalone filters to remove a high concentration of specific impurities.

Some of the contaminants that are targeted by KDF are iron, hydrogen sulfide, chlorine, lead, and other heavy metals.

UV Filters

UV, or ultraviolet, filters don’t technically filter your water. They use a UV light to kill living organisms as water passes through the system.

Most filters don’t have small-enough pores to remove microscopic bacteria, viruses and other microbes. That’s where UV comes in. A UV purification system sends ultraviolet light into these contaminants, damaging their DNA, killing them and preventing them from replicating.

Ultraviolet filtration doesn’t work on turbid or sediment-heavy water, so this type of system is usually installed as a post filter stage downstream of a more complex entire-home system.

✅ What do Whole House Water Filters Remove?

Different whole home water systems remove different contaminants:

Activated Carbon Filters Remove:

• Chlorine
• Tastes
• Odors
• Pesticides, and herbicides
• Trihalomethanes

Sediment Filters Remove:

• Sand
• Silt
• Dust
• Dirt
• Rust
• Turbidity

Whole House RO Systems Remove:

• Sediment
• Bacteria
• Minerals
• Salts
• Chemicals
• Heavy metals

Air Injection Systems Remove:

• Iron
• Manganese
• Sulfur

UV Systems Remove:

• Bacteria
• Parasites
• Fungi
• Viruses
• Algae

⭐ What Are the Benefits of Whole House Water Filters?

Whole house water filters have the following benefits:

Filter your Entire Water Supply

A whole house filter provides you with clean drinking water – but that’s not all. Whole house water filters ensure that your entire water supply is filtered, meaning that all the water that flows through your plumbing and appliances is free from contaminants. This is good news if you want to extend the lifespan of your pipes, fixtures, washing machines, shower heads, and more.

Targeted Contaminant Removal

Because there are so many whole house filter systems to choose from, you can find a system that meets your exact contaminant removal requirements. Whether you’re dealing with high iron or sediment in your well water, or you want to vastly improve the quality of your chlorinated city water, there’s a whole house water filtration system for you.

Protect You from Dangerous Impurities

Whole house water filtration systems remove some of the most dangerous contaminants in our water, including chemicals, disinfection byproducts, and heavy metals like lead. These contaminants have a whole host of potential health effects. By removing them from your water, you should feel safe drinking from the tap.

Improve Skin and Hair Health

Showering in filtered water has numerous skin and hair health benefits. If you install a whole house system that can remove chlorine, your skin and hair will retain their natural oils, which are typically stripped by chlorinated water. This should mean that you deal with fewer dry skin and hair issues, and your risk of eczema and dandruff is reduced.

Environmentally Friendly

Whole house systems improve the taste and quality of your tap water, so you’ll be happy to drink your home’s water supply instead of buying single-use plastic bottles. Plus, a whole house water filtration system improves the efficiency of your appliances and helps them to last longer, so you’ll use less energy and reduce your waste.

🆚 Whole Home Water Filters Vs Softeners

Water filters and softeners for whole home use are often confused.

Actually, there’s an important difference between the two. While a filter removes contaminants, producing filtered water, a softener removes hardness minerals, producing soft water.

If limescale is your biggest water quality issue and you need to prevent scale buildup, you don’t need a water filter – you need a water softener. Test your water to work out what it contains, and what you need to remove.

If necessary, you can install a whole house water system alongside a water softener to provide double the benefits in your home.

💰 Should you Buy a Whole House Water Filtration System?

Whole house water filters are incredibly valuable units, but that doesn’t mean they’re right for everyone.

Whole home systems are some of the most expensive water treatment solutions available. If your budget doesn’t stretch as far as a filter for your whole home, you may be better off with a smaller, point of use filtration system.

Consider your biggest reason for installing a water filter system.

If you just want to make your water safe to drink, you may as well save money with a targeted tap water filter, like an under-sink filter, a countertop filter, or a pitcher filter.

If you’re keen to protect your plumbing and appliances from contaminants, or enjoy clean water for showering or bathing, a whole house filtration system is going to be more suitable.

Work out the cost of the system you’re interested in, including the cost of installation and maintenance, to determine whether you can afford to own it for the next decade or so.