How Often Should You Test Well Water? A Simple Testing Schedule
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- Test your well for coliform bacteria and nitrate every year. The CDC and EPA both recommend at least yearly testing for private wells.
- Test for arsenic, lead, iron, manganese, hardness and fluoride every 3 to 5 years, or once a year if they are common in your area.
- Test right away after a flood, repairs, a new pump, or any change in taste, color or smell.
- Use the schedule builder below to get a list made for your home.
If you are on a private well, nobody tests the water for you. City water is tested many times a month, but private well owners are responsible for their own testing.
The good news is that a simple yearly routine covers most risks. This guide gives you that routine, the extra tests worth doing and the moments when you should test right away.
Your well testing schedule
Your well testing schedule
Tick what applies to your home and well. You get a list of tests for this year, every 3 to 5 years, and right now.
What to test every year
| Test | Why it matters | Safe limit |
|---|---|---|
| Total coliform bacteria | A sign that surface water or septic waste may be getting into the well | None detected |
| E. coli | Points to fecal contamination and can cause serious illness | None detected |
| Nitrate | From fertilizer, manure and septic systems. Dangerous for babies under 6 months | 10 mg/L as nitrogen |
Spring is a good time to test, because snowmelt and rain are most likely to wash contamination into a well. Test at the same time each year so you can compare results.
Read more about each one in our guides to coliform bacteria and nitrates in well water.
What to test every 3 to 5 years
These contaminants come from the rock and soil around your well or from your plumbing. They change slowly, so a test every few years is enough unless your area has known problems.
| Test | Where it comes from | Guideline |
|---|---|---|
| Arsenic | Natural rock in many regions | 0.010 mg/L |
| Lead | Old pipes, solder and fittings | 0.015 mg/L action level |
| Iron | Natural, causes orange stains | 0.3 mg/L (taste and staining) |
| Manganese | Natural, causes black stains | 0.05 mg/L (taste), 0.3 mg/L (health advisory) |
| Hardness | Calcium and magnesium in rock | Over 7 grains per gallon is hard |
| Fluoride | Natural in some aquifers | 4.0 mg/L maximum, 2.0 mg/L secondary |
| pH | Water chemistry | 6.5 to 8.5 |
Limits from the EPA National Primary Drinking Water Regulations and EPA secondary standards.
If arsenic, uranium or radon are common in your state, test for them every year until you have a few clean results. Your state health department or county extension office can tell you what is common locally.
See our guides on arsenic, iron and manganese in well water.
When to test your well right away
- After a flood or if water pooled around the wellhead.
- After repairs, a new pump, or any work that opened the well.
- When the water changes in color, taste, smell or clarity.
- When someone gets sick with stomach problems and the water could be the cause.
- Before a baby arrives, test nitrate before you mix formula with well water.
- When you buy a home with a well. Ask for recent results, or test before closing.
- After a septic problem or new construction nearby.
If bacteria show up, shock chlorinate the well, flush it, then test again a week or two later.
Lab test or home test kit?
Home test strips are fast and cheap, and they are useful for spotting changes in hardness, iron or pH between lab tests. They are not precise enough to clear your water for bacteria, nitrate or arsenic.
For the yearly bacteria and nitrate test, use a certified lab. Your state health department lists certified labs, and many county health offices sell low cost bacteria tests.
Mail in lab kits are a good middle ground. You take the sample at home and a lab runs the tests. Our best well water test kits guide compares options.
See well water test kits on Amazon
How to take a good sample
- Use the sterile bottle from the lab. Do not rinse it.
- Take water from a cold tap that does not have a filter or softener, or take it before the treatment system.
- Remove the aerator and run the cold water for 2 to 3 minutes.
- Fill to the line without touching the inside of the cap or bottle.
- Keep it cold and get it to the lab within the time they give you, often 24 to 30 hours for bacteria.
What to do with your results
| Result | What to do |
|---|---|
| Coliform found, no E. coli | Shock the well, flush, retest. Check the well cap and seal |
| E. coli found | Stop drinking the water. Use bottled water, shock the well, find the source and retest |
| Nitrate over 10 mg/L | Do not give the water to babies. Look at reverse osmosis or a new water source |
| Arsenic over 0.010 mg/L | Use treatment such as reverse osmosis at the kitchen tap |
| Iron or manganese high | Use an iron filter or oxidizing filter for the whole house |
Keep every result in one folder or a note on your phone. Seeing the trend over the years tells you far more than one test.
Frequently asked questions
How often should well water be tested?
Test private well water for coliform bacteria and nitrate at least once a year. Test for arsenic, lead, iron, manganese, hardness and fluoride every 3 to 5 years, and right away after floods, repairs or any change in the water.
What is the best time of year to test well water?
Spring is a good time, because rain and snowmelt are most likely to carry contamination into the well. Testing at the same time each year makes results easier to compare.
How much does it cost to test well water?
A basic bacteria and nitrate test often costs $30 to $60 at a county or state lab. A full panel for metals and minerals usually costs $100 to $300.
Can I test my well water myself?
Home test strips can show hardness, pH and iron, but bacteria, nitrate and arsenic should be tested by a certified lab. Mail in kits let you take the sample yourself and send it to a lab.
Should I test well water before buying a house?
Yes. Ask the seller for recent results and order your own bacteria and nitrate test, plus arsenic and lead if they are common in the area, before closing.
Sources: CDC guidelines for testing well water; EPA private wells.
