Treatment Guidance

Water Treatment Methods

Not all filters solve all problems. These guides explain exactly what each technology removes, what it doesn't, and when to use it.

Under-sink / Countertop

Reverse Osmosis

Reverse osmosis (RO) is the most comprehensive point-of-use water treatment technology available for residential use. It removes 90–99% of dissolved contaminants including PFAS, lead, arsenic, nitrates, and disinfection byproducts by forcing water through a semi-permeable membrane with pores of approximately 0.0001 microns.

Addresses

PFAS / PFOA / PFOS — 90–99% removalLead — 95–99% removalArsenic — 90–95% removal+6 more
$200–$600 for the unit; $50–$150/year for replacement filters
Flexible

Activated Carbon

Activated carbon is the most widely used residential water treatment technology. It removes chlorine, taste and odor compounds, disinfection byproducts, many volatile organic compounds (VOCs), and — with NSF/ANSI 53 certification — lead and some PFAS. It is available as pitcher filters, under-sink units, and whole-house systems.

Addresses

Chlorine and chloramine — virtually complete removalTaste and odor compounds — highly effectiveDisinfection byproducts+5 more
Pitcher filters: $25–$60 plus $5–$10/month in replacement filters
Whole-Home

Water Softener

A salt-based water softener is the standard whole-home solution for hard water. It uses ion exchange to replace dissolved calcium and magnesium — the minerals responsible for scale, soap scum, and appliance damage — with sodium ions. Softeners protect plumbing and appliances but do not address health-based contaminants.

Addresses

Scale buildup in pipes, water heaters, and appliancesSoap and shampoo lathering — softened water requires significantly less soapSpots on dishes, glassware, and shower doors+4 more
$400–$1,500 for the unit; $10–$25/month for salt depending on hardness and household size; professional installation $300–$600
Under-sink / Countertop

UV Purification

Ultraviolet (UV) water purifiers use germicidal UV-C light to inactivate bacteria, viruses, and protozoa by damaging their DNA. UV is highly effective for microbial disinfection and leaves no chemical residue in the water. However, UV does not remove any chemical contaminants — it is a disinfection technology only, not a filtration technology.

Addresses

Bacteria — 99.9%+ inactivationViruses — 99.9%+ inactivationProtozoa — Giardia and Cryptosporidium+2 more
$100–$500 for the unit; $50–$100/year for replacement lamps and sleeves
Whole-Home

Whole-House Filter

Whole-house (point-of-entry) filtration systems treat all water entering a home before it reaches any tap, shower, or appliance. They are available in a range of media types targeting different contaminants. Most systems combine a sediment pre-filter with one or more treatment stages. The right system depends entirely on what contaminants are in your specific water supply.

Addresses

Chlorine and chloramine taste/odor throughout the homeSediment, sand, and particlesIron and manganese staining+4 more
$150–$800 for the system; $100–$300/year in replacement filters depending on system type and water quality