Dataset · CC-BY-4.0 Well Water Testing
Private Well Water Testing Reference (Contaminants, Limits, Frequency)
Reference table of the contaminants the CDC recommends testing private wells for, the EPA maximum contaminant levels (MCLs) used as health benchmarks, and the recommended testing frequency. ~43 million U.S. homes rely on unregulated private wells.
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| Measure | Value |
|---|---|
| U.S. population on private wells | ~43 million |
| Minimum testing frequency (CDC) | Annually |
| Total coliform bacteria — EPA standard | 0 (none detected) |
| Nitrate — EPA MCL | 10 mg/L (as nitrogen) |
| Arsenic — EPA MCL | 0.010 mg/L |
| Lead — EPA action level | 0.015 mg/L |
| pH — recommended range | 6.5–8.5 |
| When bacterial contamination peaks | Summer (warm water 90°F+, heavy rain) |
| Acceptable lab types | EPA/state-certified or NELAP-accredited |
| Typical standard panel cost | $150–$600 |
Source: U.S. EPA National Primary Drinking Water Regulations (Maximum Contaminant Levels); U.S. CDC "Well Testing" guidance; USGS estimates of private-well reliance.
License: Free to reuse under CC-BY-4.0. Please cite HomeAllClear (https://homeallclear.com/data/private-well-water-testing-reference/).
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