Guide · Home care

Whole House Water Filters

What a whole house water filter does, who usually changes the cartridge, and the general steps to do it safely.

Where to start

Housing leaking, cracked or stuck?
Stop, keep the water off to the filter, and call the owner. See the general steps.
Weak shower or cloudy water?
The cartridge may be due. See how often.
Asked to change the cartridge?
Check who changes it first, then follow the maker's steps. Start with who does what.

The short version

Some homes have a filter where the water line comes into the house. It catches sand, grit and rust, and some filters also improve taste and smell. It quietly works on every drop of water in the home.

Like any filter, it fills up over time, and a full filter slowly starves the faucets and showers of pressure. If you are unsure about anything, please ask first. That is always the right call.

What the filter does

A whole house filter usually sits on the main water line, often in a basement, garage, crawl space or utility closet. Inside a clear or solid plastic housing is a cartridge that traps sediment, and some cartridges use carbon to reduce chlorine taste and smell.

The housing holds water under the same pressure as the rest of the home's plumbing, which is why it has to be handled with care.

Who changes it

In most rentals, changing the cartridge is the owner's job. Please check the lease or ask the owner. If the home is on a private well, the filter is part of the well system, so it always stays with the owner or a licensed professional.

If the owner has asked you to change the cartridge on a home with city water, follow the maker's instructions for that exact filter, and ask for a quick walk through the first time.

How often

Many makers suggest a new cartridge about every six months, or sooner if the water flow drops, but it depends on the water and the filter. The maker's instructions are the best guide.

A drop in water pressure
Cloudy water
A change in taste

These can all mean the cartridge is due.

The general steps

Every filter is a little different, so this is the general shape, not a replacement for the maker's steps.

Set a bucket and towels under the housing.
Turn off the water to the filter. Many filters have a valve on each side, and some have a bypass valve.
Relieve the pressure. Many housings have a small pressure release button on top. If not, open a faucet after the filter to let the pressure out.
Never unscrew a housing that is still under pressure. Makers say to release the pressure first, every time.
Loosen the housing with the filter wrench, then turn it by hand.
Remove the old cartridge, then clean and rinse the housing the way the maker's instructions say.
Check the rubber O ring for cracks or flat spots, and use only the lubricant the maker recommends.
Put in the new cartridge, then tighten the housing the way the maker says. Most start by hand, and some call for a small extra turn with the filter wrench. Never overtighten it, since that can make the next change much harder.
Turn the water back on slowly, let out trapped air with the release button if there is one, and check for drips.
Run a cold faucet for a few minutes to flush the new cartridge.

If the housing will not budge, leaks after you finish, or looks cracked, stop, keep the water off to the filter, and call the owner.

Try it

Your whole house filter checklist

From the guide’s own checklist. Tick each one as you go. These are examples; your home may need others.

0 of 7

Know where the filter is and who changes it
Water off and pressure released before opening the housing
O ring checked and cared for the way the maker says
Housing tightened the way the maker says, never overtightened
Drips checked after the water comes back on
Date of the change written on the tag
Low pressure, cloudy water or leaks reported

An everyday example

A resident noticed the shower had gone from strong to weak over a couple of months. They mentioned it to the owner, who checked the filter tag and saw it had not been changed in almost a year. The owner turned off the water to the filter, pressed the release button, swapped in a new cartridge and hand tightened the housing. The pressure came right back, and the owner set a reminder for the next change.

Test yourself

How much do you remember?

4 quick questions from this guide, with a one line why for each. Totally optional, no sign in, and your answers are never saved.

From The Perfect Series

Go deeper with The Perfect Plumbing

A water filter is one small part of a home's plumbing. The Perfect Plumbing walks through the whole system, from shutoff valves to water heaters, with clear notes on who does what.

See The Perfect Series

Keep this guide handy

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From the Bunklow shop

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Bunklow Home Guide 109: Whole-House Potable Water Cartridge Filter Replacement and DepressurizationA printable guide to whole-house potable water cartridge filter replacement and depressurization, in plain steps.
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Plumbing and Water Checklist PackThe Plumbing and Water checklists in one pack, fillable on screen or printable.
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This guide shares general educational information to help you, and is not legal advice or a substitute for a licensed professional. Bunklow does not inspect, repair or service plumbing or water systems. Rules differ from state to state and town to town, so please check your state and local law and your lease, follow the maker's instructions, and get local help from a licensed plumber for repairs.