Pick a whole-house filter by matching its media to the problem in your water, then size it for your home's peak flow, usually 6 to 12 gallons per minute. Use sediment prefilters for grit, carbon for chlorine taste (catalytic carbon for chloramine), and dedicated iron, manganese or sulfur filters on well water. UV disinfection needs clear, low-iron water ahead of it.
A whole-house (point-of-entry) system treats every tap, shower and appliance. It is a plumbing project, so get the type and size right the first time.
Match the media to the problem
| Problem | Treatment |
|---|---|
| Sand, grit, rust flakes | Sediment filter, staged from coarse to fine |
| Chlorine taste and odor | Activated carbon |
| Chloramine | Catalytic carbon |
| Iron and manganese | Oxidizing filter (air injection, birm, greensand) |
| Rotten-egg smell | Air injection oxidation or chlorine injection with contact time |
| Bacteria | UV disinfection, NSF/ANSI 55 Class A |
| Hardness | Softener; see softener sizing |
Size for peak flow
Undersized filters cause pressure drops in the shower when the dishwasher runs. Count fixtures likely to run together. Typical showers use about 2 gallons per minute, faucets 1 to 2, and a washing machine 2 to 3. Many homes land between 6 and 12 gpm. Check the filter’s rated flow and pressure drop, and match its ports to your main line, usually 3/4 or 1 inch.
Order of treatment on well water
A typical sequence is sediment, then iron or sulfur treatment, then softener, then carbon, then UV last. UV must come after anything that clouds or stains the water, because particles and iron shield microbes from the light.
Installation and upkeep
Install a bypass valve so you can service the system without shutting off water. Put pressure gauges before and after cartridge housings so you can see when a filter is loading up. Budget for cartridge and media changes and, for UV, an annual lamp change.
Before you buy
Test first; our well water testing guide lists what to check. Then confirm each claim on the certification listing. Browse whole-house systems.
Common questions
What flow rate do I need for a whole-house filter?
Most homes need 6 to 12 gallons per minute at peak. Count fixtures that run at once and check the filter's rated flow at an acceptable pressure drop.
What micron sediment filter should I use?
Many systems use a 20 to 50 micron prefilter followed by a 5 micron filter. Going straight to a fine filter on dirty water clogs it quickly.
Does a whole-house filter remove hardness?
No. Hardness needs a softener. Some salt-free systems reduce scale but do not soften.
Do I need a whole-house filter if I have city water?
Only if you want chlorine or chloramine taste and odor reduced at every tap, or have sediment issues. Many city users only need a kitchen filter.