How Often Should I Test My Well Water?

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.

Minimum Recommended Testing Schedule

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

Test Immediately After These Events

• Flooding — any flood event that reached the well casing or area around the wellhead
• Earthquake — can shift geology and open new contamination pathways
• Well service or repair — any time the well is opened, test bacteria afterward
• Nearby land use change — new agricultural operation, construction, or industrial activity nearby
• Change in water appearance — new color, turbidity, or sediment
• Change in taste or smell — new metallic, sulfur, or chemical taste or odor
• Unexplained illness — gastrointestinal illness in multiple household members with no other explanation
• Positive test by a neighbor — shared aquifer contamination can spread

Special Situations Requiring More Frequent Testing

• Infant in the household — test nitrates and bacteria before and during the period when infant formula is being prepared
• Pregnant woman — test nitrates and bacteria, especially in agricultural areas
• Immunocompromised person — annual bacteria testing minimum; consider quarterly
• Near active agriculture — test nitrates twice yearly (spring and fall) to catch seasonal peaks
• Older well (pre-1980) — test more frequently; aging casings increase contamination risk

Keeping Records

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.