Why does my well pump keep turning on and off?

You hear it before you see it: a click from the pressure switch, the pump runs for a moment, another click, and a few seconds later it happens again. That is short cycling, and it is worth dealing with quickly. A pump is a mechanical device that eventually wears out, and limiting how often it starts is one of the things that extends its life¹.

Why the tank is usually the cause

The pressure tank stores water against a cushion of compressed air so the pump can rest between uses. When that cushion is lost, there is almost nothing stored. Pressure drops the moment a tap opens, the pump starts, pressure shoots back up, and the pump stops².

The Private Well Class, a program of the University of Illinois and the Rural Community Assistance Partnership, lists four causes of frequent cycling¹:

Cause	What is happening	Usual fix
Waterlogged tank	The tank has lost its air cushion	Restore the air charge
Leaking bladder or diaphragm	Air and water are no longer kept apart	Replace the bladder or the tank
Tank too small	Too little water stored between pump starts	A larger tank, sized by a professional
Water use has changed	Livestock, a garden or an addition is drawing more than the system was built for	Review the pump and tank with a contractor

Source: The Private Well Class. The fixes are a summary; a licensed well contractor should confirm the cause.

A pressure switch that isn’t working properly can also be behind it, which is why the professional inspection recommended by the National Ground Water Association includes a check of both the pressure tank and the switch³.

What you can check yourself

Stay on the safe side of the pressure switch cover. These checks need no tools beyond a tire gauge.

1. Watch the pressure gauge. With a tap running, note where the needle is when the pump starts and when it stops. Normal operating pressure is somewhere between 30 and 60 psi¹. A needle that swings between the two settings in a few seconds means the tank is storing very little.
2. Make sure nothing is running. If the pump starts when no tap is open, water is leaving the system somewhere. A running toilet or a dripping outdoor faucet is the cheap explanation, so rule those out first.
3. Check the tank’s air charge. With the power off and the tank drained, the air pressure at the valve on top should be about 2 psi below the pump’s cut-in setting⁴. Our pressure tank guide has the steps and a chart.
4. Look for sediment. Sand is abrasive and wears pumps and piping¹. Grit in the toilet tank or in water drained from the pressure tank is worth mentioning to the contractor.

When to call a professional

Call a licensed well contractor or pump installer¹ if any of these is true:

• The pump cycles on and off frequently, or you notice a drop in pressure or flow³.
• The air charge won’t hold, or water comes out of the tank’s air valve, which points to a failed bladder⁴.
• Taps sputter air, especially during heavy use. In a low-yield well the pump may be drawing the water level down to its intake, which can overheat and damage the motor¹.
• The pump has stopped and won’t restart. Some systems have a low-pressure cut-off switch, typically set to 10 psi, that shuts the pump down until it is reset by hand¹. Find out why it tripped before resetting it.
• The water has turned cloudy, discolored or foul-smelling. Wellowner.org says to test it immediately³. See cloudy or sandy well water and well water testing.

Ask the contractor what they found and write it down with the date: the cut-in and cut-out settings, the tank’s air charge and its size. Next time something changes, you will have numbers to compare.

Preventing it

• Check the tank’s air charge about every six months¹.
• Have the well inspected once a year. The National Ground Water Association recommends an annual professional inspection with a flow test, a check of the pump motor and a check of the pressure tank and switch³.
• Tell the contractor when your water use changes. A new bathroom, irrigation or animals can leave a pump and tank that were sized for a smaller demand cycling constantly¹.
• Ask about a larger tank if the well is slow. A well that produces only a few gallons a minute needs a large tank, so the pump can refill it gradually when nobody is using water².