On this page
A private well needs its owner to do four things: test the water at least once a year, check the pressure tank's air charge, notice when the pump starts cycling wrong, and keep the wellhead sealed against surface water and pests. None of that is hard. The part most owners skip is the test, and the CDC is direct that nobody else is going to do it.
A typical well has a submersible pump down the casing, a pressure tank in the house that stores water under air pressure so the pump does not run for every glass, a pressure switch that starts the pump when the tank drops to the cut-in pressure and stops it at the cut-out, and a wellhead cap above ground. Many wells also feed a softener or a filter; the softener guide covers that.
How do you test well water every year?
Test well water at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH, using a state-certified laboratory, plus whatever the local health department says is common in your area. The lab supplies the bottles and the sampling instructions; the health department helps read the results. It is the one task on this page with a health outcome.
The CDC's guidelines for testing well water say private wells are not regulated, treated, or monitored by officials, so the owner is responsible; to test at least once every year for total coliform bacteria, nitrates, total dissolved solids, and pH; to ask the local health department what other germs or chemicals to test for in your area; to use a state-certified laboratory; and to check the well every spring for mechanical problems.
- Call the county or state health department, or look up the state's list of certified drinking water laboratories. Many health departments test for free or cheaply.
- Get the lab's sample bottles and follow their sampling instructions exactly; a coliform sample contaminated at the tap tells you nothing.
- Test for the CDC's four, plus whatever the health department says is common locally (arsenic, radon, and specific pesticides are regional).
- Read the results with the health department if anything is flagged. A positive coliform result usually means shock-chlorinating the well and retesting; nitrates and other chemicals mean treatment. Do not guess.
- File the results with the house. The hardness number in the report is also the setting your softener needs.
How do you check the pressure tank?
Check the pressure tank's air charge once a year: with the pump's breaker off and the system drained, the air pressure at the tank's valve should read about 2 psi below the pump's cut-in pressure. Add air if it is low; if water comes out of the air valve, the bladder has failed and the tank needs replacing. A wrong charge makes the pump short cycle and wears it out.
The pressure tank has an air charge on one side of a bladder or diaphragm and water on the other. When the air charge is wrong, the pump short cycles and wears out.
- Find the pump's cut-in pressure on the pressure switch (often 30 or 40 psi; the switch is labeled 30/50 or 40/60).
- Turn off the pump's breaker. Open a tap until water stops flowing, so the tank is empty of water.
- Check the air pressure at the tank's valve (like a tire valve) with a tire gauge. It should read about 2 psi below the cut-in pressure. Done when: you have a reading.
- If low, add air with a compressor or a bicycle pump to the right pressure. If water comes out of the air valve, the bladder has failed and the tank needs replacing.
- Turn the breaker on and watch a cycle: the pump should run until cut-out, stop, and not restart until a good amount of water has been used. A pump that restarts within seconds has a tank problem.
What should you check at the wellhead?
Each spring, walk to the wellhead and confirm the cap is tight and sealed, the casing is uncracked and stands above any flooding, the ground slopes away from it, and nothing that could contaminate the water (fertilizer, pesticides, fuel, the septic drainfield) sits within the setbacks the health department gives. A sealed, well-drained wellhead is most of the protection a private well has.
Walk to the wellhead each spring. The cap should be tight and sealed, with no gaps where insects or mice can enter and no cracks in the casing. The ground should slope away from the casing so surface water does not run down it. Nothing should be stored, sprayed, or spread near it: fertilizer, pesticides, fuel, and the septic drainfield all need distance, and the health department can tell you the setbacks. Keep the casing tall enough to stay above any flooding.
What are the signs of trouble?
Falling pressure or sputtering taps (air in the lines, a failing pump, or a dropping water table); short cycling (the tank); the pump running constantly (a leak in the house, a stuck switch, or a pump that can no longer reach cut-out); dirty, cloudy, or sandy water (a failing screen, a dropping level, or casing damage); a change in taste or smell (test, do not wait for the year); a tripping breaker (the pump motor). Any of these is a call.
When should you stop and call a pro?
Call a licensed well contractor for anything involving the pump, the wiring, the pressure switch, the well casing, or the water level; for a positive coliform test that persists after shock chlorination; and for any treatment system design. Do not open the wellhead cap beyond a visual check, and never lower anything into the well. A well with a pump that has failed is a house with no water, so keep the contractor's number where the emergency contacts live.
In a new home with a new well, get the well log (depth, yield, casing details) and the pump's model and install date from the builder or the driller; they are required for any future repair and are nearly impossible to get years later.
What should you record?
Every test result with the date and lab, the pressure tank's air charge and the date checked, the pump's model, depth, and install date, the well log, and the contractor. The pattern in the test results over years is how you notice a slow change. Set the yearly test, the tank check, and the wellhead walk as recurring tasks, and put the test in spring, when the CDC suggests the mechanical check too. On a property with a septic system, the septic guide is the other half.
Common questions
What should I test well water for, and how often?
The CDC says at least once every year for total coliform bacteria, nitrates, total dissolved solids, and pH, using a state-certified laboratory, and to ask the local health department what else is common in your area. Test more often if the taste, smell, or color changes, after flooding, or after work on the well.
The pump turns on and off every few seconds when a tap runs. What is that?
Short cycling, and the usual cause is a pressure tank that has lost its air charge or has a failed bladder. Check the tank's air pressure with the pump off and the system drained; it should be a couple of psi below the pump's cut-in pressure. A waterlogged tank needs replacing. Short cycling wears out the pump, so do not leave it.
Can I work on the well myself?
The pressure tank's air charge, the wellhead cap and seal, and the annual test are owner tasks. The pump, the wiring, the pressure switch, and anything down the well are a licensed well contractor's job. Working on a submersible pump means pulling it up the well casing with equipment; it is not a homeowner project.
What should you do next?
If the water has not been tested in the last year, order the sample bottles this week. It is the one task on this page with a health outcome, and it costs less than a tank of gas.
