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Private Well Guide

  • Start Here
  • Testing
    • What to Test For
    • How Often to Test
    • Read Your Results
  • Contaminants
    • Coliform & E. coli
    • Nitrates
    • Arsenic
    • Lead
    • PFAS
    • Radon
    • Iron & Hard Water
  • Kits vs Labs
    • Best Test Kits
    • Tap Score vs Certified Lab
  • Treatment
    • Shock Chlorination
    • Treatment Options

Reading Results

How to Read Your Well Water Test Results (MCLs, ppm and ppb Explained)

Illustration: a bar chart of test results with a limit line
Decode your well water lab report: mg/L vs ppm vs ppb, EPA primary vs secondary standards, what ‘ND’ and ‘TNTC’ mean, and what to do if a result is high.
Private Well Guide

Plain-English well water testing and treatment for rural homeowners.

Guides

  • Well Testing Guide
  • What to Test For
  • Contaminants
  • Read Your Results
  • Treatment Options

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Not medical advice: for health decisions, use a state-certified lab and your state or local health department.

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