The pressure switch is a small box bolted near the pressure tank, and it decides when your pump runs. It is also the single most common reason a well system misbehaves, which makes it worth understanding before anyone quotes for a pump.
Most of what people want from it is simple: where it is, how to adjust it, and how to get the pump running again after it has cut out.
What Does a Well Pump Pressure Switch Do?
A pressure switch closes its contacts when system pressure drops to the cut-in figure, which starts the pump, and opens them at the cut-out figure, which stops it. Common settings are 30/50 or 40/60 psi, with a 20 psi gap between the two.
Key Takeaways
- Cut-in starts the pump, cut-out stops it, usually 20 psi apart.
- The larger nut moves both settings, the smaller nut moves cut-out only.
- Change the cut-in and you must reset the tank precharge to match.
- A blocked sensing port makes a healthy switch behave like a failed one.
- Everything inside the cover is at line voltage.
Where to Find It
The switch sits on the pressure tank itself or on the pipe within a few feet of it: a small grey or black box with a removable cover, connected to the water line by a thin tube or a threaded port. On a submersible system it is always above ground, never down the well, which is the whole point of the design.
Adjusting the Settings
| What you want | Which nut | Direction |
|---|---|---|
| Raise both cut-in and cut-out | The larger nut | Clockwise |
| Lower both | The larger nut | Counter-clockwise |
| Widen the gap, raising cut-out only | The smaller nut | Clockwise |
| Narrow the gap | The smaller nut | Counter-clockwise |
Move a quarter turn at a time and let the system cycle before judging the result. The mechanism behind the two springs is described in this note on the pressure switch.
One step gets skipped constantly and it matters more than the adjustment itself: after changing cut-in, reset the pressure tank precharge to 2 psi below the new figure. A tank charged for the old setting leaves the pump short cycling, which is what wears out motors.
When the Pump Will Not Restart
Many switches include a low-pressure cutoff that latches out when pressure falls below cut-in, so the pump cannot start into an empty system and destroy itself. Switches with a lever are reset by holding it. Switches without one reset by restoring pressure and cycling the breaker.
If it latches out again immediately, the system is not holding pressure, and the cause is upstream: a lost prime, a dropped water level, or a leak. Our guide to telling whether a well pump is bad works through that order.
The Fault Nobody Checks
The switch senses pressure through a small port or tube, and on iron-rich or sandy water that passage silts up. The switch then reads a pressure the system does not have, so the pump runs on when it should stop or refuses to start when it should run.
From outside this looks exactly like a failed switch, and plenty get replaced when clearing the port would have fixed it. Check the passage before buying anything.
Repair or Replace
- Pitted or burnt contacts: replace the switch, it is inexpensive.
- Blocked sensing port: clear it, the switch is fine.
- Pump short cycling: check the tank precharge before touching the switch.
- Switch chatters: usually a waterlogged tank, again not the switch.
- No voltage at the switch: the fault is upstream, in the breaker or wiring.
Rows three and four are the ones worth remembering. A pressure switch is often blamed for a pressure tank problem, and swapping it changes nothing. The servicing routine that catches this is in our guide to annual pump servicing, and where the pump is a three wire submersible, the starting components live in the control box rather than here.
Frequently Asked Questions
How do you reset a pressure switch on a well pump without a lever?
Without a lever, a well pump pressure switch is reset by restoring pressure to the system and cycling power at the breaker, since the low-pressure cutoff only latches out when pressure falls below cut-in. Prime the pump first if it has lost water. Holding contacts closed by hand is live electrical work and not a homeowner job.
How do you adjust a well pump pressure switch?
Adjust a well pump pressure switch using the two nuts under its cover. The larger nut moves cut-in and cut-out together, and the smaller nut changes only the cut-out, widening the gap between them. Turn clockwise to raise pressure, a quarter turn at a time, and reset the tank precharge afterward.
Where is the pressure switch on a well pump?
The pressure switch on a well pump sits on the pressure tank or on the pipe within a few feet of it, usually a small grey or black box with a removable cover and a thin tube or threaded port connecting it to the water line. On a submersible system it is above ground, never down the well.
How do you test a well pump pressure switch?
Test a well pump pressure switch by checking whether it closes at the cut-in pressure marked on it and opens at cut-out, comparing both against the system gauge. Pitted or burnt contacts and a blocked sensing port are the usual faults. Testing involves live line voltage, so it belongs to a qualified electrician.
Well Pump Parts at Ken’s Distributing
Ken’s Distributing supplies well pump components and controls across the Franklin Electric range, and complete replacement units including 4 inch submersible well pumps.
Tell us the symptom and the pressures you are reading at cut-in and cut-out, and we will help work out whether the switch, the tank or the pump is the actual problem.