Well Water Check: Annual Testing Calendar and Record

Test private well water at least once a year for total coliform bacteria, nitrate, pH, and total dissolved solids (TDS). Add locally recommended tests and confirm their timing with your health department. Test sooner after flooding, well repairs, changes in water quality, or other contamination concerns—even if your annual test was recent. Choosing among certified labs, mail-in kits, strips, and meters is covered in the well water tester comparison. CDC testing guidance

Choose a recurring month for routine testing, then keep separate dates for local tests and follow-up samples. The calendar below is a planning tool; an event or concerning result takes priority over the next scheduled date.

If contamination is suspected, change water use first

If you know or suspect that harmful germs or chemicals have entered your well, use bottled water or another safe source for drinking, cooking, and food preparation while you get advice from your health department. Do not wait for a confirmation sample or treatment purchase to take this step. CDC treatment guidance

The next precautions depend on the problem:

• Flooded well: Do not drink or wash with the water. Stay away from flooded pump equipment because of electric shock risk. Get a well or pump contractor’s help with inspection, cleaning, and disinfection before restarting the pump, and coordinate recovery and testing with your health department. EPA flood response guidance
• Suspected fuel or unidentified chemical contamination: Avoid drinking or using the water pending specific health department advice. Boiling does not remove chemicals. CDC treatment guidance
• Germ contamination: Use safe replacement water for drinking, cooking, and food preparation. If none is available and the concern is germs, CDC recommends following boil-water guidance while the well is being treated. Boiling is not a remedy for a possible chemical problem. CDC treatment guidance

For a nitrate or arsenic concern, use safe replacement water for drinking, cooking, and food preparation. Ask your health department for contaminant-specific guidance about bathing, laundry, and other household uses based on the substance and concentration found. CDC testing and follow-up guidance

Your annual and event testing calendar

When	What to schedule or record
Same month each year	Total coliform bacteria, nitrate, pH, and TDS, plus locally recommended tests that are due.
Before the collection date	Confirm the laboratory’s instructions, obtain its containers, and arrange sample delivery.
After a local contamination notice or significant nearby change	Contact the health department promptly about targeted testing. Examples include flooding, land disturbance, construction, and new industrial activity.
After any well-system repair or replacement	Arrange testing with the lab or contractor; have them specify collection timing around the work and any treatment.
When taste, color, or smell changes	Arrange prompt testing matched to the change. Use the precautions above if harmful contamination is suspected.
When someone becomes pregnant or a child joins the household	Arrange testing rather than waiting for the annual date; ask whether the ongoing schedule should change.
After corrective treatment	Test to verify that treatment worked before resuming drinking or other restricted uses.

CDC and EPA recommend annual testing and identify these event triggers. EPA also advises considering more frequent testing when small children, older adults, or someone pregnant or nursing lives in the home. Neither source gives one extra testing interval for all such households. CDC testing guidance, EPA testing frequency, CDC treatment guidance

CDC also recommends checking the well for mechanical problems each spring. You can coordinate appointments, but a water sample does not assess pump or well condition. See the well water inspection guide for that work. CDC well-check guidance

Keep all four annual tests on the list

A package called a “basic well test” may not contain all four recommended annual measurements. Check the actual test list.

Annual test	What it helps you understand
Total coliform bacteria	An indicator of possible contamination pathways. It does not identify every harmful germ.
Nitrate	A chemical concern that can arise from fertilizer, waste, and other sources; elevated levels are especially concerning for babies.
pH	How acidic or basic the water is, which can affect plumbing corrosion and water characteristics.
TDS	The overall amount of dissolved substances, useful for understanding changes in taste and mineral buildup.

A favorable result on these four tests does not establish that untested contaminants are absent. CDC annual tests and their purposes

Give local tests their own due dates

Ask your health or environmental department which additional contaminants matter at your address and how often to test for each. CDC identifies arsenic, lead, mercury, radium, pesticides, herbicides, and volatile organic compounds among the possibilities. EPA connects nearby intensive agriculture with nitrate, nitrite, pesticides, and coliform concerns; lead-containing plumbing with lead and copper testing; and nearby fuel or industrial sources with appropriate chemical testing. CDC local testing guidance, EPA conditions and suggested tests

There is no universal three-year schedule for a broader panel in this guidance. Write down the local recommendation, who provided it, and the next due date. Our state resources guide can help you find the relevant agency.

Arrange the lab work, then close the loop

Use a state-certified drinking-water laboratory. Confirm that its certification covers the requested analyses in your state. If results are also needed for a property transaction, confirm the recipient’s requirements before sampling. EPA provides links to state laboratory certification programs. EPA laboratory directory

Tell the lab whether this is routine, event-related, or treatment-verification testing. Follow its instructions for containers, collection location, preparation, storage, and delivery timing. Record the sample location and whether the water passed through treatment. For more detail on choosing analyses, use the well water testing guide.

When results arrive, save the complete report and ask the health department to explain concerning findings and any repeat-test schedule. EPA public-system drinking-water limits may appear as comparison benchmarks; federal public-system rules do not apply to private wells. A report addresses only the substances tested. EPA results guidance, CDC private-well responsibilities

Copy this testing record

Keep one entry per sampling event, with the full laboratory report attached. Preserve the reported units and wording rather than reducing everything to “passed.”

Record field	Your entry
Well address or identifier	__________
Routine annual testing month	__________
Reason for this sample	Annual / local recommendation / event / follow-up
Collection date, time, and tap	__________
Treatment operating at collection	__________
Lab name and report identifier	__________
Total coliform result	__________
Nitrate result, units, and reporting form	__________
pH result	__________
TDS result and units	__________
Additional tests and results	__________
Recent flooding, repairs, or water changes	__________
Agency or contractor advice, contact, and date	__________
Water-use precautions and corrective action	__________
Follow-up test due date and result	__________
Next annual date and separate local-test dates	__________

Set the next reminders when you file the report. Keep unresolved follow-up actions visible until the recommended work and verification testing are complete.