| Conditions or Nearby Activities | Recommended Analysis |
| Recurrent gastrointestinal illness | Coliform bacteria |
| A suspicion that household plumbing contains lead | pH, lead, copper |
| Radon in indoor air or region is radon rich | Radon |
| Hand soap does not later or there is a scaly residue | Hardness |
| Hard water residue – water treatment needed to remedy hardness | Manganese, iron |
| Stained plumbing fixtures, laundry | iron, copper, manganese |
| Objectionable taste or smell | Hydrogen sulfide, corrosion, metals |
| Water appears cloudy, frothy or colored | Color, detergents |
| Corrosion of pipes, plumbing | Corrosion, pH, lead |
| Rapid wear of water treatment equipment | pH, corrosion |
| Nearby areas of intensive agriculture | Nitrate, pesticides, coliform bacteria |
| Coal or other mining operation nearby | Metals, pH, corrosion |
| Gas drilling operation nearby | Chloride, sodium, barium, strontium |
| Odor of gasoline or fuel oil, and near gas station or buried fuel tanks | Volatile organic compounds (VOC) |
| Dump, junkyard, landfill, factory or dry-cleaning operation nearby | VOC, Total dissolved solids (TDS), pH, sulfate, chloride, metals |
| Salty taste and seawater, or a heavily salted roadway nearby | Chloride, TDS, sodium |
