Most private well owners test their water far less often than recommended — or never. Here is the testing schedule the EPA recommends, what events should trigger immediate testing, and how to keep track of your results.
| Test | Frequency | Why |
|---|---|---|
| Coliform bacteria | Annually | Contamination pathways change over time |
| Nitrates | Annually | Levels fluctuate with rainfall and land use |
| pH | Every 3 years | Gradual changes from geology and precipitation |
| Total dissolved solids | Every 3 years | General quality indicator |
| Iron and manganese | Every 3 years | Stable in most wells; more if staining occurs |
| Arsenic | Once, then every 5 years | Stable geologically but worth confirming |
| Comprehensive panel | When moving into new home | Establish baseline for all contaminants |
Keep all test results in a folder with the date, lab name, and any actions taken. This record is valuable when you sell the home — it demonstrates responsible well maintenance. It also lets you track trends over time: gradually rising nitrates may indicate a developing problem before levels become unsafe.
Set a calendar reminder. The most common reason wells go untested is simply forgetting. Set an annual reminder in your calendar for spring — after snowmelt and spring rains, bacteria and nitrate levels are often at their seasonal peak, making spring the best time for routine annual testing.
Test for coliform bacteria annually at minimum, since contamination pathways can change over time. Immunocompromised households should consider testing quarterly instead.
Arsenic only needs to be tested once and then rechecked every 5 years, since it's geologically stable. A comprehensive panel covering all major contaminants should be run once when you move into a new home to establish a baseline.
Test right away after flooding, any well service or repair, nearby land use changes (new agriculture, construction, or industrial activity), a change in water color/taste/smell, unexplained illness in the household, or if a neighbor on the same aquifer tests positive for contamination.
Yes — test nitrates and bacteria before and during the period when infant formula is being prepared. Nitrates are especially important since infants are more vulnerable to nitrate-related health effects than adults.
If you're near active agriculture, test nitrates twice a year — spring and fall — since levels can spike seasonally with fertilizer application and runoff.
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