Whole-House Water Filters: Do You Need One?

Short answer: Most homes on safe tap water don't need a whole-house water filter.^{Source [1]}^{Source [3]} One makes sense when testing shows a problem that affects every tap, such as radon, certain volatile chemicals, iron, rotten-egg odor or hard water.^{Source [1]}^{Source [2]}^{Source [5]} If your only concern is the water you drink and cook with, a certified filter at one tap usually does the job for far less money.^{Source [1]}^{Source [3]}

Below is how whole-house systems differ from tap filters, what they cost, and the trade-offs to know before you buy.

What a whole-house water filter is

A whole-house filter, also called a point-of-entry (POE) system, is installed on the water line where it enters your home. It treats all the water in the house: kitchen, bathrooms, laundry and outdoor taps.^{Source [1]}^{Source [3]}

A point-of-use (POU) filter treats water at one faucet or location. Pitchers, faucet-mount filters, refrigerator filters and under-sink units are all point-of-use.^{Source [3]} CDC suggests point-of-use filters if you only need to filter the water you drink and cook with.^{Source [1]}

"Whole-house filter" covers several different technologies, not one product:

Sediment (mechanical) filters catch sand, silt and clay. They don't remove dissolved substances and are often paired with other equipment.^{Source [5]}
Activated carbon reduces chlorine taste and odor, and some units are certified for radon, many organic chemicals and trihalomethanes (byproducts of chlorine disinfection).^{Source [4]}^{Source [5]}
Water softeners swap hardness minerals for sodium or potassium.^{Source [4]}
Oxidizing filters turn dissolved iron, manganese and hydrogen sulfide into particles the filter traps.^{Source [4]}^{Source [5]}
Neutralizing filters treat acidic water.^{Source [5]}
UV disinfection kills bacteria and viruses but doesn't remove chemicals.^{Source [4]}

No single unit removes everything. Depending on your water, you may need more than one stage.^{Source [3]}

When a whole-house filter makes sense

Problems you can breathe or bathe in

For most contaminants, the risk comes from drinking the water, so treating one tap is enough. EPA's consumer fact sheet notes an exception: radon, disinfection byproducts and some organic chemicals easily turn into gases and may be inhaled, for example while showering. A point-of-entry device can reduce these.^{Source [2]} CDC likewise says to consider a whole-home filter if you need to remove a harmful substance, such as certain volatile organic chemicals, from all your water, including the water you bathe and clean with.^{Source [1]}

Carbon has limits here. University of Missouri Extension says a whole-house carbon unit can handle low levels of radon and organic chemicals but is not designed for persistently high levels. In that case, a different water supply may be the safest answer.^{Source [5]}

Problems that affect pipes, fixtures and laundry

Some problems are about the whole plumbing system rather than health:

Hard water that leaves scale. Softening is the cheapest way to remove hardness.^{Source [4]}
Iron, manganese or a rotten-egg smell that stain fixtures and laundry. Oxidizing filters usually treat the entire supply.^{Source [4]}^{Source [5]}
Acidic water, which can pull lead and copper out of household pipes. Neutralizing filters treat all the water entering the home.^{Source [5]}

EPA notes that point-of-entry devices can also reduce aesthetic problems such as scaling, staining and odor.^{Source [2]}

Private wells

Well owners are responsible for testing their own water. CDC recommends testing at least once a year for harmful germs and chemicals, and contacting your health department for advice on what to test and how to find a state-certified lab.^{Source [1]} Our guide to choosing a water test explains the options. If you test for radon in your home's air, our radon testing guide covers that side.

When you probably don't need one

If you're on a public water system, read your utility's annual water quality report first. It lists contaminants that were detected and how the levels compare with standards.^{Source [1]}^{Source [3]} Our guide on how to read a water quality report walks through it. Minnesota's health department says most residents do not need home treatment to protect their health.^{Source [3]}

Common reasons a whole-house unit is overkill:

You just want better-tasting drinking water. A carbon pitcher or faucet filter certified to NSF/ANSI Standard 42 addresses taste and odor.^{Source [1]} Compare options in our water filter pitcher guide.
You're worried about lead. Lead usually enters water from lead pipes and solder inside some homes.^{Source [2]} Treating water where it enters the house doesn't address lead picked up after that point. Test first with our lead in water testing guide, then use a filter certified for lead at the tap you drink from.^{Source [1]}
Your fridge filter is the only concern. See whether a fridge water filter is worth it.

Taste, smell and appearance are not reliable signs of safety either way. Harmful germs and chemicals often don't change how water looks or tastes.^{Source [1]}

Trade-offs to know

Removing chlorine can let germs grow

Chlorine in tap water kills germs, and many filters remove it along with other substances.^{Source [1]} CDC warns that if you install a whole-home filter that removes chlorine or other disinfectants, more germs may grow in your plumbing.^{Source [1]}

Poor maintenance can make water worse

Every system needs upkeep: changing filters, disinfecting, backwashing or cleaning out scale.^{Source [3]} Minnesota's health department warns that units that aren't maintained lose effectiveness, and in some cases can make water quality worse and make you sick.^{Source [3]} Its treatment guide says harmful bacteria can grow on carbon filters, and an overdue carbon filter can become saturated and start releasing contaminants back into the water.^{Source [4]}

Some systems change your water chemistry

Sodium: softening with sodium chloride adds sodium to the water, which may be a health issue for some people.^{Source [4]} Missouri Extension advises people with heart problems to discuss this with their physician.^{Source [5]}
Corrosion: softening, aeration and anion exchange may make water more corrosive to pipes, a health concern if you have copper or lead plumbing.^{Source [4]}

Whole-house reverse osmosis is rarely practical

Reverse osmosis removes a wide range of contaminants, but household systems are built for one tap. Rhode Island's health department says whole-house RO isn't practical because the systems waste about 75% of the water that runs through them.^{Source [6]} Minnesota lists whole-house RO at $5,000 to $12,000, compared with $300 to $1,500 for a point-of-use unit.^{Source [4]}

What whole-house systems cost

The Minnesota Department of Health publishes cost ranges for common systems. They are based on quotes from 2017 and research in 2018, so current prices may be higher. The low end is for units homeowners install themselves; the high end is for professional installation.^{Source [4]}

System (whole house)	Upfront cost	Ongoing cost
Activated carbon	$500 to $3,000	Filter replacement, extra water to backwash or disinfectant^{Source [4]}
Water softener	$200 to $3,000	$50 to $300 a year for salt^{Source [4]}
Oxidizing media (iron, manganese)	$1,500 to $3,000	Backwash water, chemicals, media replacement^{Source [4]}
Adsorptive media (arsenic, fluoride)	$2,400 to $4,500	$700 to $900 a year^{Source [4]}
UV disinfection	$250 to $800	About $100 a year^{Source [4]}
Reverse osmosis	$5,000 to $12,000	$250 to $500 every 1 to 2 years^{Source [4]}

For comparison, a point-of-use carbon filter costs $10 to $100, with $10 to $100 every few months for replacement filters.^{Source [4]}

How to choose a whole-house filter

Test first. Know what is in your water before you buy. If it's free of harmful germs and chemicals, you may not need a filter at all.^{Source [1]}
Match the system to the problem. Pick a unit designed for your specific contaminant, and check the label for exactly what it removes. Filters that remove germs often don't remove chemicals, and the reverse.^{Source [1]}
Look for certification. Choose a unit certified by NSF, UL or WQA for the contaminant you care about, where certification exists.^{Source [3]} Relevant NSF standards include 42 (taste and odor) and 53 (health effects such as cyst reduction).^{Source [1]}
Check maintenance before you buy. Ask how often filters or media need replacing, where you get them and what they cost.^{Source [5]}
Use a licensed installer if you hire one. Minnesota advises checking that the installer is a licensed plumber or water conditioning contractor.^{Source [3]} Rules vary by state.
Test again after installation to confirm the system is working.^{Source [3]}

If anyone in your home has a weakened immune system, CDC suggests talking with a healthcare provider and a water treatment specialist, and avoiding changing filters yourself.^{Source [1]}

Frequently asked questions

Do I need a whole-house water filter?

Usually not if you are on public water that meets standards. Health agencies say most people don't need home treatment to protect their health. A whole-house unit makes sense when testing shows a problem in all your water, such as certain volatile chemicals, radon, iron or hardness.

How much does a whole-house water filter cost?

Minnesota health officials list point-of-entry carbon systems at about $500 to $3,000, based on 2017 and 2018 prices, with ongoing filter and backwash costs. Specialized systems for iron or arsenic cost more, and whole-house reverse osmosis ran $5,000 to $12,000.

Is a whole-house filter better than an under-sink filter?

Not for drinking water alone. An under-sink or other point-of-use filter treats the water you drink and cook with, costs less and is often enough. A whole-house unit is for problems that matter at every tap, such as chemicals that turn into vapor in the shower.

Does a whole-house filter remove chlorine?

Many carbon whole-house units do. CDC notes that removing chlorine from all your water may let more germs grow in your home's plumbing, so weigh that trade-off and keep up with maintenance.

Can a whole-house filter remove lead?

Lead usually comes from pipes and fixtures inside the home, so a filter at the point of entry can miss lead picked up after it. Test for lead and use a filter certified for lead at the tap you drink from.