Private Well Annual Testing Calendar: What to Test and When

EPA notes that private well owners are responsible for testing and maintaining their own drinking water. A simple annual calendar prevents testing from becoming a one-time event only after a problem appears.

Test annually for total coliform bacteria, nitrates, total dissolved solids, and pH, and retest after flooding, repairs, nearby spills, or sudden changes in taste, odor, or appearance.

Use a certified drinking water lab and keep results in one folder so trends are visible over time.

Use current primary sources before making health or water-quality decisions. For this topic, start with EPA, CDC, NSF, or the product certification database that applies to the exact filter model.

Use the date of your last laboratory sample as the starting point for the next twelve-month cycle. The goal is not to test everything every month; it is to keep a reliable baseline and add targeted testing when the well, plumbing, or surrounding land changes.

For a basic annual check, schedule total coliform bacteria, nitrate, total dissolved solids, and pH. Ask the lab whether your sample bottle, preservation method, and delivery window are correct before collecting the sample.

Flooding, well or pump repairs, a broken well cap, nearby chemical spills, construction, or a sudden change in taste, odor, color, or pressure are reasons to contact a certified laboratory or local health department. A filter can change appearance or taste, but it cannot tell you which contaminant caused a result.

If the household includes an infant, pregnant person, older adult, or someone with a medical condition, ask a local health professional whether a shorter testing interval is appropriate.

Choose treatment from the contaminant and concentration in the report, not from a general claim such as clean water or multi-stage filtration. A carbon filter may address some taste and odor concerns, while nitrate, arsenic, bacteria, or PFAS require a product and process matched to the specific result.

After installation, follow the product maintenance schedule and retest when the original result was a health concern. The post-treatment sample is the only way to confirm that the selected treatment is working at the tap where water is consumed.

Keep the lab report, well construction details, treatment model, installation date, cartridge changes, and follow-up results together. A short log makes it easier to spot a trend and gives a professional the information needed to troubleshoot.