GroundRosterWell Water Testing: What to Test For and How Often
Municipal water is tested constantly by someone else. Your well is tested exactly as often as you test it. The good news: the testing that matters is cheap and simple, and most of it goes through your state or county health lab.
Every year, no exceptions
- Total coliform bacteria and E. coli: the standard screen for whether surface contamination is reaching your water.
- Nitrate: from fertilizer, livestock, or septic effluent. Especially critical with infants in the house.
Test in the same season each year (spring is common; high water tables reveal problems), and additionally after floods, after any well or plumbing work, and whenever taste, odor, or color changes.
Every 3 to 5 years, and when buying
A broader panel: pH, hardness, iron, manganese, total dissolved solids, and, depending on your region's geology, arsenic, radon, uranium, and fluoride. If you are buying a home with a well, run the full panel during due diligence alongside a flow test; our buyer's checklist covers how the pieces fit, and FHA/VA financing often requires water testing anyway.
Where to test
Use a state-certified lab; most state health departments run one or maintain a list, and many county health departments sell sample kits. Basic bacteria and nitrate tests are inexpensive; full panels cost more but are a rounding error next to the purchase they inform. The state pages on this site link each state's relevant agencies.
Reading the results
- Bacteria present: confirm, shock-chlorinate, retest. Recurring hits mean a pathway problem: cap, casing, or nearby contamination source.
- Nitrate elevated: look for the source. On properties with septic, a failing drainfield is a prime suspect; the crossover symptoms are in our drain field guide.
- Aesthetic issues (iron staining, rotten-egg odor, hardness): treatable with the right equipment. Match treatment to the specific result, not to a salesperson's bundle.
When the fix needs a licensed pro
Chronic bacteria, casing or cap repairs, well deepening or hydrofracturing for yield, and proper decommissioning of an old well are licensed well-contractor work. Costs for the common jobs are in our well drilling and pump repair guides, and free quotes route to licensed well contractors near you.
Common questions
How often should I test my well water?
Bacteria (total coliform and E. coli) and nitrate every year, plus any time the water changes taste, color, or smell, after flooding, or after any work on the well. Run a broader panel every few years and a full panel when buying a home.
My well water tested positive for coliform. Now what?
Do not panic; do act. Retest to confirm, shock-chlorinate the well, and retest again. Repeat positives mean finding the pathway (a bad well cap, casing crack, surface water intrusion, or a nearby septic issue), and a licensed well contractor is the right call.