EPA & USGS Data 2025 · 180,000 Well Users
Naturally occurring in groundwater. Long-term exposure increases cancer risk.
chemicalFrom road salt, septic systems. Causes salty taste at high levels.
chemicalIndicates possible contamination from surface water or sewage.
biologicalFrom copper plumbing. Causes blue-green staining and GI issues.
metalIndicates fecal contamination. Immediate health risk if detected.
biologicalNaturally occurring mineral. Beneficial at low levels, harmful at high levels.
chemicalCauses staining and metallic taste. Not a health hazard but affects water quality.
metalFrom old pipes and plumbing fixtures. No safe level for children.
metalCauses black staining. Health concerns at high levels especially for children.
metalFrom industrial pollution. Damages nervous system at high levels.
metalCommon in agricultural areas from fertilizer runoff. High levels dangerous for infants.
chemicalIndustrial chemicals that don't break down. Linked to cancer and immune issues.
chemicalAgricultural runoff. Multiple compounds with various health effects.
chemicalNaturally occurring radioactive gas. Second leading cause of lung cancer.
radiologicalNaturally occurring. Causes bitter taste and laxative effect at high levels.
chemicalOverall mineral content. Affects taste and indicates water quality.
physicalNaturally occurring in granite bedrock areas. Kidney damage at high levels.
radiologicalFrom industrial solvents, gasoline. Liver and kidney damage risk.
chemicalCalcium and magnesium content. Causes scale buildup in pipes and appliances.
physicalAcidity/alkalinity measure. Ideal range 6.5-8.5 for drinking water.
physical600 ZIP codes with well water data in Montana