The short answer
On a private well in Northern Virginia, the pressure switch is the small box on a pipe near the pressure tank. It turns the well pump on when your water pressure falls to one number and off when it climbs to another. Most are set at 30 and 50 psi, or 40 and 60. When the switch chatters, clicks on and off fast, won’t kick on, or won’t shut off, the cause is the switch, the pressure tank or the pump, and the gauge next to it tells you which.
How the switch works
Open a faucet and the pressure tank pushes water out until the pressure drops to the switch’s cut-in number. The switch closes, the pump starts, and it runs until the pressure reaches cut-out. Then the switch opens and the pump rests. A 30/50 switch turns the pump on at 30 and off at 50, a 20 psi spread. The tank’s air charge should sit 2 psi under cut-in: 28 for a 30/50 switch, 38 for a 40/60.
That rhythm is what keeps a pump alive. Franklin Electric, a big maker of submersible well motors, rates motors up to 3/4 horsepower for at most 300 starts a day, and 1 to 5.5 horsepower motors for 100. Too many starts wear the spline and bearings and overheat the motor. Long, steady cycles off a healthy tank are what let a pump last.
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Read the gauge first
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| What the gauge does | What it usually means |
|---|---|
| Climbs and drops fast while the pump clicks on and off every few seconds | The pressure tank has lost its air. The switch is doing its job, far too often. |
| Hovers right at cut-in while the switch buzzes or chatters | A clogged sensing tube under the switch, or worn contacts |
| Falls to zero and the pump never starts | No power, burned contacts, or a low-pressure cutoff that tripped |
| Climbs but never reaches cut-out, and the pump runs and runs | A worn pump, a well that can’t keep up, or a leak in the drop pipe |
| Sits at cut-out and the pump keeps running | Welded contacts. Turn the pump’s breaker off. |
It chatters
A buzzing, chattering switch is the contacts opening and closing many times a second right at cut-in. Three usual causes: a waterlogged pressure tank that makes the pressure jump, a clogged little nipple or tube the switch reads the pressure through, or pitted contacts. Chattering burns the contacts fast and is hard on the pump. Start with the tank: how to tell if a well pressure tank has failed.
It won’t kick on
- The breaker. Most well pumps have their own 240 volt breaker. Check it first.
- The low-pressure cutoff. Many switches have a lever on the side that shuts the pump off if the pressure ever drops too far, to protect a pump that ran the well dry. The reset is in your switch’s manual, and on most it means holding the lever up for a short while until the pressure builds. Never with the cover off, and if the pressure doesn’t climb, let go and call.
- Burned contacts. Inside the cover, the contacts can pit and stop closing. That’s a new switch.
No water at all in the house? What to check when a well pump stops working goes through it in order, from the breaker to the control box.
It won’t shut off
If the pump keeps running past cut-out, either the contacts welded shut or the pump can’t build enough pressure to reach cut-out. Either way, turn the pump’s breaker off. A pump that runs nonstop, or pulls a well dry, burns itself up, and a pump costs a lot more than a switch.
Look, don’t touch
A well pressure switch has 240 volts on its terminals whenever the breaker is on. Read the gauge, listen to the switch, check the breaker. The inside of the switch is a job for a plumber.
What a new switch costs
Our plumbers replace a pressure switch for $450 to $609: a new pressure switch at the tank, set to your system’s cut-in and cut-out pressures, and the system run through full cycles before we leave. Before we replace anything, we test the pump, the wire and the tank, so you pay for only what failed. Every well price we charge is on our well pump price page, and the well pump estimator gives you a range in a minute.
If the tank turns out to be the cause, see well pressure tank problems. If the pressure is low everywhere, start with low water pressure on a well. Well work is part of the plumbing work we do across Northern Virginia, from switches to whole pumps: our well pump page has the rest. And for the other parts of the house that click, blink and beep, our guide to error codes and warning lights covers them.
Book it
A plumbing diagnosis visit is $49, or $250 after hours, and you get the price of the fix before we start. Call (703) 997-9757, day or night, or book online with the problem already filled in. Every current deal is on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What should my well pressure switch be set at?
Most homes run 30/50 or 40/60: the pump starts at the first number and stops at the second. Either way, the pressure tank’s air charge should be 2 psi under the cut-in number.
Why does my well pressure switch keep clicking?
If the pump clicks on and off every few seconds when you run water, the pressure tank has usually lost its air. The switch is doing its job, just far too often, and every start wears the pump.
Can I adjust my well pressure switch myself?
The adjusting nuts are inside the cover, next to terminals with 240 volts on them. Turn the breaker off before the cover comes off, or have a plumber do it. Setting it higher than your pump can reach leaves the pump running nonstop.
How do I know if it’s the switch or the pump?
Watch the gauge. If the pressure falls past cut-in and the pump never starts, it’s the power or the switch. If the pump starts but the pressure never climbs to cut-out, it’s the pump or the well.
How much does it cost to replace a well pressure switch?
Our plumbers replace one for $450 to $609, set to your system’s pressures and run through full cycles before we leave.
