Got a lab report full of numbers and no idea what they mean? Pick the contaminant your test measured, enter your result, and this tool will tell you instantly whether it falls within EPA drinking water guidelines — plus what to do next.
| Contaminant | EPA Threshold | Standard Type |
|---|---|---|
| Hardness | 120+ mg/L commonly treated | Aesthetic (no EPA limit) |
| Iron | 0.3 mg/L | Secondary (aesthetic) |
| Manganese | 0.05 mg/L | Secondary (aesthetic) |
| Nitrate (as N) | 10 mg/L | Primary (health-based) |
| Arsenic | 10 ppb | Primary (health-based) |
| Lead | 15 ppb | Primary (action level) |
| TDS | 500 mg/L | Secondary (aesthetic) |
| Total Coliform | Any detection is flagged | Primary (health-based) |
Primary vs. secondary standards: primary standards are legally enforceable health limits for public water systems — exceeding them on a private well is a real health concern. Secondary standards are aesthetic guidelines (taste, staining, odor) with no direct health risk at typical levels.
Private well results can shift with season, rainfall, and nearby land use, so a single test is a snapshot, not a guarantee. If a primary contaminant like nitrate, arsenic, or lead comes back elevated, retest to confirm before investing in treatment, and consider a certified lab if your first test was a home kit.
Any positive coliform or E. coli result should be treated as urgent. Stop drinking the water untreated, retest, and disinfect the well and plumbing before resuming normal use.
See our full checklist of what every private well owner should test for and how often.
See the Testing Checklist →