Well Water by County

How to test your well water

Last reviewed:

Nobody tests a private well for you. In Pennsylvania, for example, DEP recommends yearly tests and says to always use a state-certified lab[1]. Here's the process the state labs we've reviewed describe.

1. Find a certified lab (or a county program)

Use a lab certified by your state for the specific tests you need. Certification is per test, so a lab can be certified for bacteria and not for radon[2]. Some counties run their own programs: Wake County, NC, for example, sends staff to collect samples for a fee[3]. Start with your county page. Each one lists programs, labs, and whether a lab takes mail-in samples.

2. Get the lab's bottles

Use only bottles the lab gives you. Bacteria bottles are sterile, and some bottles contain preservatives. The NH state lab rejects samples in other containers[4]. Penn State's mail-in kit includes a cooler, shipping box, bottles, instructions and a submission form[5].

3. Collect the sample

  1. Lead/copper first-draw (if ordered): let water sit in the pipes at least 6 hours (overnight is best). Fill the first-draw bottle with the very first water from the tap[4][6].
  2. Pick the right tap: use a clean indoor cold-water faucet, not an outdoor one or a leaky one. If you recently chlorinated the well, wait until the chlorine is gone[4].
  3. Remove the aerator and run the water. Penn State says to run it about five minutes. The NH state lab says to clean the faucet rim with dilute bleach and run it 1 minute[4][6]. Follow your own lab's instructions.
  4. Fill the bacteria bottle without touching the inside of the bottle or cap. Leave any pill or powder in it[6].
  5. Radon vials must be filled slowly to a crown with no air bubbles[4].

4. Keep it cold and beat the clock

Refrigerate or ice the samples, but don't freeze them. Bacteria samples generally must be tested within 30 hours of collection, and NH's state lab allows 48 hours for radon and nitrate[4][6]. Labs limit bacteria samples near weekends. Penn State won't accept them on Fridays, and the NH state lab stops at noon on Fridays and the day before a holiday[4][5]. If you mail samples, use guaranteed overnight delivery[4][5].

5. Read the results

Compare results to drinking-water standards. Watch the units: mg/L equals ppm, and µg/L equals ppb[3]. Several states point well owners to the free Be Well Informed tool, which explains health effects and treatment options[2][3]. Before you buy treatment, BSC Labs suggests sending your lab report to at least three treatment companies to compare[7].

Next: What to test for.

Sources

  1. PA DEP - Private Wells: Water Testing
  2. NHDES - Water Testing Guidance for Private Well Users (April 2026)
  3. Wake County, NC - Well Water Testing
  4. NH Public Health Laboratories - Water Testing Guide & Sample Collection Instructions
  5. Penn State AASL - Drinking Water Testing
  6. Penn State AASL - How to Collect a Water Sample
  7. BSC Labs - Testing Your Water