| Recurring gastro-intestinal illness |
Coliform bacteria |
| Household plumbing contains lead |
pH, lead, copper |
| Radon in indoor air or region is radon rich |
Radon |
| Corrosion of pipes, plumbing |
Corrosion, pH, lead |
| Nearby areas of extensive agriculture |
Nitrate, pesticides, coliform bacteria |
| Coal or other mining operations nearby |
Metals, pH, corrosion |
| Gas drilling operations nearby |
Chloride, sodium, barium, strontium |
| Dump, junkyard, landfill, factory, gas station, or dry-cleaning operation nearby |
Volatile organic compounds, total dissolved solids, pH, sulfate, chloride, metals |
| Odor of gasoline or fuel oil, and near gas station or buried fuel tanks |
Volatile organic compounds |
| Objectionable taste or smell |
Hydrogen sulfide, corrosion, metals |
| Stained plumbing fixtures, laundry |
Iron, copper, manganese |
| Salty taste and seawater, or a heavily salted roadway nearby |
Chloride, total dissolved solids, sodium |
| Scaly residues, soaps don’t lather |
Hardness |
| Rapid wear of water treatment equipment |
pH, corrosion |
| Water softener needed to treat hardness |
Manganese, Iron |
| Water appears cloudy, frothy, or colored |
Color, detergents |
| https://www.epa.gov/sites/production/files/2015-11/documents/2005_09_14_faq_fs_homewatertesting.pdf |
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