Drinking water contaminants

What each one is, the federal limit, how to test for it, and which systems in our database are certified to reduce it.

Contaminant	Concern	EPA limit	Systems	Certified
Chlorine bleach or swimming pool smell, chemical taste	Household	4 mg/L (as Cl2) (MCL)	31	8
Chloramine chlorine-like taste or smell	Household	4 mg/L (as Cl2) (MCL)	20	4
PFAS	Health	4 ppt each for PFOA and PFOS (MCL)	19	10
Lead	Health	15 µg/L (0.015 mg/L) (Action level)	15	7
Iron orange, red or brown stains on fixtures, dishes and laundry, metallic taste	Household	0.3 mg/L (SMCL)	18	0
Manganese black or brown stains on fixtures and laundry, bitter metallic taste	Health and household	0.05 mg/L (SMCL)	12	0
Hydrogen sulfide rotten egg smell, sometimes only from the hot tap, black or yellow stains on fixtures	Household	No federal limit	14	0
Hardness white scale on faucets, showerheads and kettles, spots and film on glassware	Household	No federal limit	17	1
Bacteria	Health	Zero for total coliform and E. coli (MCLG)	14	5
Sediment cloudy or muddy water, sand or grit in faucet aerators and toilet tanks	Household	No limit for household water	32	6
Volatile organic compounds (VOCs)	Health	5 µg/L each for benzene, TCE and PCE; 2 µg/L for vinyl chloride (MCL)	21	5
Arsenic	Health	10 µg/L (0.010 mg/L) (MCL)	10	5
Nitrate	Health	10 mg/L as nitrogen (MCL)	7	4
Fluoride white spots or streaks on children's teeth (dental fluorosis) at elevated levels	Health and household	4.0 mg/L (MCL)	10	6
Copper blue-green stains on sinks, tubs and fixtures, metallic or bitter taste	Health and household	1.3 mg/L (Action level)	11	5
Uranium	Health	30 µg/L (0.030 mg/L) (MCL)	1	1

MCL: enforceable maximum contaminant level. SMCL: non-enforceable secondary standard for taste, odor and staining. Action level: the trigger for utility treatment requirements (lead and copper).