Well Water Testing Schedule: What to Test For in Every Season
No utility tests a private well — that job belongs to the owner. This seasonal schedule tells you what to test for in spring, summer, fall and winter, which events should trigger an extra test, and how to interpret the results.
· CWT Editorial Team · 8 min read
More than 40 million Americans drink from private wells, and not one of those wells is covered by the Safe Drinking Water Act. There is no utility sampling your water, no annual report in the mail and no one who will call if something changes. Testing is the owner's responsibility — and most owners test far less often than they should.
The good news is that a sensible schedule is neither expensive nor complicated. Below is a season-by-season plan built on EPA and state health department recommendations, followed by the events that should always trigger a test.
The Baseline Every Well Owner Needs
If you have never had your well tested, or cannot find the last results, start with a comprehensive baseline before worrying about seasons. A standard well panel from a state-certified laboratory ($150 – $300) should include:
- Total coliform and E. coli bacteria — the primary indicator of contamination from septic systems, animals or surface water.
- Nitrate and nitrite — from fertilizer, manure and septic leachate; dangerous to infants under six months and in pregnancy.
- pH, hardness, alkalinity and total dissolved solids — determine corrosion risk and treatment needs.
- Iron, manganese and sulfate — the usual causes of staining, odor and bad taste.
- Arsenic, lead and copper — arsenic is naturally present in groundwater in many regions; lead and copper come from plumbing.
- Sodium and chloride — elevated levels hint at road salt, saltwater intrusion or softener discharge reaching the well.
Add radon in water and uranium if you live in a granite or bedrock region (much of New England, the Appalachians, the Rockies and the Southwest), and volatile organic compounds if there is a gas station, dry cleaner or industrial site within a half mile. Keep the report; every future test is compared against it.
Spring: Bacteria and Nitrates After Snowmelt
Spring is the highest-risk season for most wells. Snowmelt and heavy rain raise the water table, flood low-lying well heads and flush fertilizer, manure and septic effluent into shallow groundwater.
Test in spring: total coliform / E. coli and nitrate. These are inexpensive ($50 – $100 together) and fast — bacteria results take 24 to 48 hours.
Also in spring: walk the well head. The casing should extend at least 12 inches above grade (more in flood-prone areas), the cap should be tight and vermin-proof, and the ground should slope away from the well. Look for cracks in the casing, a missing or loose sanitary seal, and any pooling water. Check that fuel tanks, pesticide storage and livestock are at least 50 to 100 feet away, and the septic drain field at least 50 feet (more where state codes require).
Summer: Heavy Use, Heavy Rain and Agriculture
Summer brings peak water demand, thunderstorms and the height of the growing season.
Test in summer if: you had any positive bacteria result in spring (retest after shock chlorination), you are in an agricultural area (nitrate and, every few years, a pesticide or herbicide screen), or your well runs dry or produces cloudy water during drought. Low water levels can draw in sediment and concentrate naturally occurring contaminants such as arsenic.
Watch for: a sudden change in taste, odor or color after storms, which signals surface water reaching the well; sand or grit in aerators, which points to a failing screen or casing; and sputtering air at the tap, which usually means the pump is drawing down the well.
Fall: The Deep-Dive Panel
Fall, when the water table is typically lowest and most stable, is the best time for the broader tests that do not change much season to season.
Every three to five years in the fall: arsenic, uranium, radon in water, fluoride, hardness, iron, manganese, sodium, chloride and a VOC scan. Many of these are naturally occurring and shift slowly, but they decide whether you need treatment such as reverse osmosis (arsenic, uranium, nitrate), aeration (radon), or iron and manganese filtration.
Every year in the fall: repeat bacteria and nitrate if you have livestock, a nearby farm, or a septic system more than 20 years old.
Fall is also a good time to service treatment equipment: sanitize the softener brine tank, replace UV lamps (most are rated for 12 months), swap sediment and carbon cartridges, and have the pressure tank and well pump inspected before winter.
Winter: Protect the System
Winter is less about sampling and more about prevention. Frozen or cracked casings, pitless adapter failures and power outages are the main threats.
- Insulate exposed well house plumbing and keep the cap sealed; a cracked cap is the most common entry point for insects and surface water.
- Keep road salt and de-icers well away from the well head; chloride and sodium rise quickly in shallow wells near treated driveways.
- If the well is in a pump house, make sure it is heated enough to prevent freezing and that there are no rodent nests around the casing.
- After any power outage that lets the pressure drop to zero, run water until it is clear and consider a bacteria retest, since backflow can introduce contamination.
Events That Should Always Trigger a Test
Regardless of season, test your well immediately after any of the following:
- Flooding that reaches or surrounds the well head — assume the well is contaminated until bacteria and nitrate results come back clean.
- Any change in taste, odor, color or clarity.
- Repairs or replacement of the pump, casing, pressure tank or any plumbing — new parts introduce bacteria.
- A new septic system, livestock operation, construction, drilling or chemical spill nearby.
- Recurring gastrointestinal illness in the household with no other explanation.
- A new baby or a pregnancy in the home — test for nitrate and bacteria before using well water for formula.
- Buying or selling the home. Many lenders require it, and it protects both sides.
If a bacteria test comes back positive, shock-chlorinate the well following your state's guidelines, flush, and retest. Repeated positives usually mean a construction defect or a nearby contamination source and call for a well contractor's inspection. For ongoing protection, ultraviolet disinfection ($600 – $1,500 installed) is the standard point-of-entry solution. Local well specialists are listed in our directories — try Fort Wayne, Kalamazoo or Provo — or schedule a free water test and we will match you with one.
Frequently Asked Questions
- How often should I test my private well?
At minimum, test for total coliform bacteria and nitrate once a year — spring is ideal — and run a broader panel for metals, minerals and other naturally occurring contaminants every three to five years. Test immediately after flooding, repairs or any change in the water.
- What does a well water test cost?
A basic bacteria and nitrate test runs $50 to $100 at a state-certified lab. A comprehensive baseline panel is typically $150 to $300, and specialized tests such as radon, uranium, pesticides or PFAS add $50 to $500 each. Many county health departments offer subsidized testing.
- My well water tastes fine. Do I still need to test?
Yes. The contaminants that matter most for health — bacteria, nitrate, arsenic, uranium, radon — have no taste, odor or color at harmful levels. Taste tells you about minerals and sulfur, not safety.
- Can I treat well water instead of testing?
Treatment should follow testing, not replace it. Without results you cannot choose the right technology — a UV light does nothing for arsenic, and a softener does nothing for bacteria. Test first, then treat, then test again to confirm the system is working.
Topics: well water testing, private well, well water, coliform bacteria test, nitrate well water, well water treatment, water testing schedule