Why Is My Well System Turning On and Off Constantly?

What it usually looks like

• The pump clicks on and off rapidly while you run a shower or fill the tub
• Water pressure surges and drops at the faucet in a pulsing rhythm
• The pressure gauge needle swings fast between the cut-in and cut-out numbers
• The pressure tank feels heavy and sounds solid when you knock on it, top to bottom
• The pressure switch contacts are pitted, buzzing or arcing
• Breakers trip or the well house smells hot after a long shower

Likely causes, most common first

1. Waterlogged pressure tank

   A bladder tank holds a charge of air above a rubber diaphragm. That air compresses as the pump fills the tank and pushes water out between cycles. When the bladder tears or the air leaks out through the Schrader valve, the tank fills with water, there is no cushion, and the pump cycles on every drop of pressure. This is the cause nine times out of ten.

2. Wrong pre-charge in the tank

   Even an intact bladder needs the right air pressure, normally two psi below the pump's cut-in setting. A tank that was never charged correctly, or that was charged while full of water, delivers a fraction of its rated drawdown and the pump cycles far more than it should.

3. Pressure switch set too narrow or failing

   The switch should have about a 20 psi spread between on and off, such as 40/60. Corroded contacts, a clogged nipple below the switch, or a spring that drifted will shorten the spread and cause rapid cycling. Iron and manganese in Mason County well water love to pack that small nipple with sludge.

4. A leak between the pump and the tank

   A failed check valve, a leaking pitless adapter or a cracked drop pipe lets pressure bleed back down the well. The pump then cycles on and off even when no water is being used in the house, which is a different pattern from cycling only during use. A check valve in the well house is a plumbing repair; a leak down the casing is pump company work.

5. An undersized tank for the pump

   A high-output pump paired with a tiny tank fills it in seconds. Each cycle is short by design, and the pump sees far more starts per day than it was built for. Upsizing the tank solves it.

6. Low-yield well or clogged screen

   If the well cannot keep up, some pumps are protected by a low-pressure cutoff or a pump-saver that shuts them down and restarts them, which can look like cycling. This is more common in the shallow wells near Hood Canal and on the Key Peninsula during late summer, and it is a well and pump question rather than a tank question.

Safe things to check yourself first

• Watch the pressure gauge while someone runs a faucet. Note the cut-in and cut-out pressures and how fast the needle moves between them.
• Knock on the pressure tank from top to bottom. A healthy tank sounds hollow on top and solid near the bottom. Solid all the way up means it is full of water.
• Turn the pump breaker off, open a faucet until pressure drops to zero, then check the air valve on top of the tank with a tire gauge. Water coming out of the air valve means a ruptured bladder.
• Look for water leaking around the tank, the switch, the fittings and the well cap.
• Note whether the pump also cycles when nobody is using water. If so, suspect a leak or a check valve, not just the tank.
• Check the age of the tank. A sticker or stamp gives the date, and tanks older than ten years are often at the end.

How we diagnose and fix it

• Check the pre-charge with the system drained and compare it to the switch settings, then test the bladder for rupture.
• Replace waterlogged tanks with a correctly sized Well-X-Trol or Amtrol bladder tank, charged to match the switch, with a new tank tee, gauge and relief valve.
• Clean or replace the pressure switch and its nipple, and set the spread to the right range for your pump and household.
• Isolate the system to test for a failing check valve when the pump cycles with no demand, and replace the check valve in the well house when that is where the leak is.
• Upsize the tank or add a second one when the pump output is more than the existing tank can buffer.
• Tell you plainly when the tests point past the well house to the pump, the drop pipe or the pitless adapter, and refer you to a well pump company for that part of the job.

Questions people ask