Which filter for which contaminant
There is no "best water filter" — there is only the filter certified for the thing that is actually in your water. A carbon pitcher removes lead and does nothing for fluoride, nitrate or arsenic. A softener fixes hardness and radium and nothing else. Pick your contaminant below.
Not sure what you have? Look up your city's EPA water quality report first .
- Lead Lead causes irreversible developmental harm in children at any measurable level. Needs: Carbon certified for lead (NSF 53)
- PFAS ("forever chemicals") PFAS do not break down in the body or the environment and are linked to cancer and immune effects. Needs: Reverse osmosis (NSF 58)
- Arsenic Long-term arsenic exposure is a known cause of bladder, lung and skin cancer. Needs: Reverse osmosis (NSF 58)
- Fluoride Most people searching this want it removed by choice rather than because of a violation. Needs: Reverse osmosis (NSF 58)
- Nitrate Nitrate is an acute risk to infants under six months — it causes methemoglobinemia ("blue baby syndrome"). Needs: Reverse osmosis (NSF 58)
- Chlorine taste and smell Almost always an aesthetic complaint rather than a health risk — the chlorine is there on purpose. Needs: Basic activated carbon (NSF 42)
- Chloramine Chloramine tastes and smells like chlorine but resists the filters that remove chlorine. Needs: Catalytic carbon
- Hard water (calcium and magnesium) Scale on fixtures, spotty dishes, dry skin, and shortened water heater life. Needs: Ion-exchange water softener
- Iron Orange-brown staining on sinks, laundry and toilets, plus a metallic taste. Needs: Oxidizing / air-injection filter
- Manganese Black staining, and emerging evidence of neurological effects in infants at higher levels. Needs: Oxidizing / air-injection filter
- Chromium-6 (hexavalent chromium) The "Erin Brockovich" contaminant — a probable human carcinogen when ingested. Needs: Reverse osmosis (NSF 58)
- Uranium Kidney toxicity from the metal itself, on top of the radiological risk. Needs: Reverse osmosis (NSF 58)
- Radium A bone-seeking radioactive element linked to bone cancer over long exposure. Needs: Ion-exchange water softener
- Bacteria and E. coli Acute illness within days, unlike the slow-burn chemical contaminants. Needs: UV disinfection (NSF 55)
- Rotten egg smell (hydrogen sulfide) The smell is unbearable, and it can mean bacterial activity in a well or water heater. Needs: Oxidizing / air-injection filter
- Total dissolved solids (TDS) Usually driven by a cheap TDS meter reading rather than by an actual health problem. Needs: Reverse osmosis (NSF 58)
- Trihalomethanes and disinfection byproducts Formed when chlorine reacts with organic matter — a side effect of the disinfection that keeps water safe. Needs: Carbon certified for lead (NSF 53)
- Copper Blue-green staining, a metallic taste, and stomach upset at higher levels. Needs: Reverse osmosis (NSF 58)
- VOCs (benzene, TCE, PCE and related solvents) Industrial solvents that reach groundwater from spills, dry cleaners and fuel storage tanks. Needs: Carbon certified for lead (NSF 53)
- Pesticides and herbicides Agricultural runoff, which peaks seasonally after spring application and heavy rain. Needs: Carbon certified for lead (NSF 53)
- Heavy metals (mercury, cadmium, barium and others) Cumulative toxicity: these build up in the body rather than clearing quickly. Needs: Reverse osmosis (NSF 58)
- Gross alpha, gross beta and strontium-90 Naturally occurring radioactivity in groundwater, common in granite and shale regions. Needs: Reverse osmosis (NSF 58)
- Radon Radon is a lung cancer risk mainly through inhalation — showering releases it into the air. Needs: Basic activated carbon (NSF 42)
- Asbestos Usually released by deteriorating asbestos-cement water mains rather than by the source water. Needs: Carbon certified for lead (NSF 53)
- Perchlorate Interferes with thyroid iodine uptake, which matters most for pregnancy and infants. Needs: Anion exchange
- 1,4-Dioxane A probable human carcinogen that resists nearly every conventional treatment. Needs: Reverse osmosis (NSF 58)