Why does my well pump keep cycling on and off?
Updated August 2026
A well pump that snaps on and off every few seconds whenever you run water is nearly always fighting a waterlogged pressure tank that has lost its air charge or ruptured its internal bladder. With no air cushion left, the tank cannot hold pressure, so the pump hits cutoff, the pressure instantly drops, and it fires right back up. Checking and restoring the tank's air pre-charge fixes most cases. A bad pressure switch or a system leak are the other causes.
Safety first: a well system runs on 240 volts, so keep the electrical parts in mind. The pressure switch, the pump wiring, and the control box carry enough current to be lethal, so shut off the well pump breaker before you open the switch cover or touch any wiring. Checking the tank's air charge with a tire gauge is safe once the pump is off and the system is drained of pressure, but leave switch calibration and wiring work to a pro if you are not confident. Never run the pump dry while diagnosing, since that burns the motor out fast.
Causes, most likely first
| Cause | How likely | The fix | Typical cost |
|---|---|---|---|
| Waterlogged pressure tank (lost air charge) | Most common | Recharge the air to 2 psi below cut-in if the bladder is intact; replace the tank if the bladder has ruptured. | $0 recharge / $200–600 tank |
| Ruptured tank bladder | Common | Water at the air-valve side confirms a blown bladder. The tank has to be replaced, not recharged. | $200–600 installed |
| Faulty pressure switch | Occasional | A worn or miscalibrated switch cuts in and out on too tight a band. Adjust or replace the switch. | $20–150 |
| Leak in the system or foot valve | Occasional | A running toilet, a pipe leak, or a leaking foot valve bleeds pressure and makes the pump refire. Find and fix it. | $50–400 |
| Clogged screen or failing pump | Rare | A fouled intake screen or a failing pump cannot keep up, causing erratic cycling. A well pro tests output. | $150–500+ |
Check these first
- Watch the pressure gauge on a draw. Rapid needle swings between cut-in and cut-out every few seconds are the signature of a waterlogged tank.
- Tap the tank. A healthy tank sounds hollow up top and solid at the bottom; a tank that sounds full of water all the way up has lost its air charge.
- Press the air valve on top of the tank with the system depressurized. Water spraying out instead of air means the bladder has ruptured.
- Rule out leaks. Shut every fixture and watch whether the pump still kicks on; a pump that cycles with nothing running points at a leak or the foot valve.
- Check the switch. Listen for chattering contacts and look for burnt or pitted points inside the pressure switch cover, with the breaker off.
Prevent it next time
Short cycling is the fastest way to wear out a well pump, so catching it early matters. Check the pressure tank's air pre-charge once a year (it should sit about 2 psi below the pump's cut-in pressure) and top it up before the tank goes fully waterlogged. Test the pump and pressure settings annually, and know that a pressure tank lasts roughly 8–12 years while the pump itself runs 8 to 15. Staying ahead of a failing tank protects the pump, which costs $800–2,500 to replace. The well-pump checklist covers the annual checks.
When to call a pro
Call a well or pump professional when recharging the air does not stop the cycling (a sign the bladder is gone), when the pressure switch is pitted or chattering, or when the pump cycles with every fixture closed and you cannot find the leak. A pressure-tank replacement runs $400–900 installed, a pressure switch $150–300, and pulling a submersible pump for testing $500–1,500 plus the pump. Do not keep letting a pump short cycle while you decide; every rapid cycle shortens the motor's life and pushes you toward the $800–2,500 pump replacement.
Most of the causes above are maintenance problems wearing a disguise. OnOtto keeps the boring prevention on schedule so the 2 a.m. version doesn't happen.
Stop chasing symptoms, free for 30 daysFrequently asked questions
How do I check the air charge in my well pressure tank?
Turn off the pump breaker, then open a faucet to drain all pressure from the system until the gauge reads zero. With the tank empty of pressure, put a tire gauge on the air valve at the top; it should read about 2 psi below your pump's cut-in setting, so a 30/50 switch wants roughly 28 psi. If it reads low, add air with a bike or compressor pump. If water comes out of the air valve instead, the bladder has failed and the tank needs replacing.
How long does short cycling take to damage a well pump?
Faster than most people expect. Pump motors are rated for a limited number of starts per day, and short cycling can multiply that by ten or more, overheating the motor and wearing the start components. A pump that might have lasted 10 to 15 years can fail in a season or two of hard short cycling. That is why a waterlogged tank is not a wait-and-see problem: fixing a $200 to $600 tank promptly protects an $800 to $2,500 pump.
Why does my well pump run even when no water is on?
That is a leak somewhere between the pump and the fixtures, different from waterlogged-tank cycling. A running toilet flapper, a dripping outdoor spigot, a pinhole in a supply line, or a leaking foot valve at the bottom of the well all bleed pressure, and the pump wakes up to replace it. Shut every fixture, watch the gauge, and if it slowly falls and the pump kicks on, hunt the leak. A foot-valve leak, which lets the whole line drain back, is a common well-specific cause.