Water pressure control adjustment nuts (C) D FriedmanMaximum Water Pump and Tank Pressure Settings
How high can we set building water pressure?

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Well pump pressure control switch maximum pressure setting:

This article describes how to adjust building water pressure by setting the water pump cut-in and cut-out pressure on the well water pump pressure control switch.

We also point to our article on how to adjust building municipal or community water pressure at a building.

Watch out: You can't just set the pump pressure as arbitrarily high as you want to. The result could be dangerous.

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How High Can we Set the Water Pressure in My Building?

Here's what can go wrong with excessive pump pressure control settings:

Reader Question: What should I do about sudden very high water pressure in my pump and well system?

Pump pressure control switch photo (C) D FriedmanI noticed that my water pressure suddenly seemed awful high and when I checked the gauge it was. I have a 6" drilled well and the shutoff pressure was reading 80# of pressure. I tried adjusting the range nut with little success.

The gap between 'on' and 'off' was way to much. (The switch, a Square-D, indicated a gap of 20-40 ) I think that I have a bad pressure switch. Any thoughts? - J.T.

Reply: Replace the pressure control switch, check and clear debris blockage in the switch mounting piping

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem.

That said, here are some things to consider based on what you've described so far:

Because you confirmed that the water pressure really is excessive by direct observation, I don't think this is a common gauge error problem and I agree that the problem is most likely with the pressure control switch. In our photo (above-left) the green arrow points to a SquareD pump pressure control switch at its typical installation location.

A well water pump pressure switch might stick in the "on" position due to debris clogging at the pressure sensing orifice, or at the switch mounting tube, or on occasion relay switch points can burn and actually weld together.

Turn Off Unsafe Water Pumps

Watch out: high pressures from a pump that is either pumping to too high a pressure control setting or that does not shut off due to a switch or wiring problem can burst water pipes or a water tank, possibly even leading to injuries, especially if your water pressure tank lacks a pressure relief valve. I would turn OFF a system pumping to or over 80 psi until the problem is diagnosed and corrected. In our photo (above left) there is indeed a pressure relief valve installed on this pump and tank system. You can see the relief valve attached just below the pressure switch mounting tube (red arrow).

How to Install a New Water Pump Pressure Control Switch

If no one had previously been attempting to adjust the pressure control switch, I'd install a new one. When you install the new switch, either replace or clean out the small-diameter (typically 1/8" or 1/4" ID NPT) pipe nipple that is used to mount the pressure switch to the piping or fitting where it is attached. In our pressure control switch photo (above left) the red arrow points to the mounting tube that we are discussing.

Watch out: As a temporary, emergency "Sunday night" repair, I have filed clean and smooth pitted, burned contact points on a relay switch (with power OFF of course), but because relay switch points are made with a protective plating on the contact point surfaces, when you file or clean burned contact points the switch may still have a short remaining life, and you risk also changing the behavior of the contact relay or even of making the switch unsafe. So it's best to replace the switch promptly.

To replace a water pump pressure control switch the installer will need to turn off electrical power to the system, remove the old switch by disconnecting its wiring and then unscrewing the switch from its mounting tube, and install the new switch in the same position. It's a good idea to label your switch wires or take some photos as well so that you wire the new switch exactly as the old one was hooked-up.

Watch out: if you do not run enough water to remove water pressure from the pressure tank, when you remove the old pressure switch you'll see water squirting out of the mounting tube. That's not necessarily so terrible if that "squirt" also cleans debris from the tube. If you drain off water pressure first, the leakage at that point will be trivial. If not, be prepared to get wet as you are screwing the new switch in place, and be prepared to dry everything out before restoring electrical power.

Don't forget to use teflon paste or tape on the threads of the mounting tube so that your new switch won't leak at the mount, but don't blob in so much pipe dope or paste that you risk clogging the switch pressure sensing orifice on the switch bottom.

You should be able to use the new pressure control switch with the factory settings for cut-in and cut-out pressure, especially if you bought one already set to one of the two standards: 20/40 psi or 30/50 psi for Cut-in and Cut-out pressures. Or see WATER PUMP PRESSURE CONTROL ADJUSTMENT if you need to adjust the pressure switch settings.

Check for Sediment Blockage at the Pump Controls

As we discuss at Water Pump Pressure Control Switch Tubing Problems, often if there is sediment or rust or debris in the water system, that small diameter pipe or even the bottom sensor openings on the pressure control switch can become clogged. The result is that the switch stops properly sensing water pressure.

At that point pressure switch behavior can go either way: the switch may fail to sense a water pressure drop and thus doesn't turn on when needed, or it may fail to sense a water pressure increase and thus does not turn off when needed. Too little water pressure is inconvenient. Too much water pressure can be dangerous.

If/when you are replacing a pump pressure control switch, check the tubing or switch mount as well as the bottom of the old pressure switch for evidence of sediment or mineral deposits or other crud that block the pressure sensing mechanism. Clean or replace blocked switch mounting tubing.

Install a Sediment Filter?

Finally, if indeed your water source is giving up debris, silt, or other sediment particles that can clog the water supply system and its controls, you should consider installing a water filter system as well. Most water filters I've seen are installed after, rather than ahead of the water pressure tank and controls. But if needed, with a few extra control valves to make filter changeout easy, it should be possible to install filtration ahead of the tank and controls, thus protecting them from sediment as well.

Increased pressure switch settings too high, lost all water pressure: check thermal reset

Reader Question: Last week I increased the cut-in cut-out pressure switch setting on my well. The system was running at 20-40 and after making the pressure switch adjustment it has been running at 40-60 just as I planned. I checked the cut-in and cut-out over several days after the change and it was working fine.

Today we found that we had zero water pressure. I looked over our system and found there is no water flowing into our pressure tank so no water is being pumped. I tested for power at the pressure switch and it is getting power but I did not check the voltage.

The well pump was here when we bought the house about 10 years ago so the pump is at least 10 years old. I don't know the specifics of the pump but the control box for the pump states 1 hp, 230 volt, single phase and includes a capacitor and some other blue device.

I assume my increasing the pressure switch seating has lead to a pump failure. Anything else I should test before running out to buy a new pump? - John M 8/34/11


John M:

Changing a pump pressure control switch from 20/40 all the way up to 40/60 has an understandable appeal: much higher water pressure, faster flow rate. But the risk is that you set a cut-off pressure that the pump simply cannot maintain. If that happens the pump might just keep on running - never reaching that 60 psi. If your pump was a submersible you might not know that the pump is spinning itself to death down in the well.

Until it stops working or until the pump overheats and shuts down on thermal overload.

Watch out: even if you reset the thermal overload switch on a pump motor, running it too long may have exceeded its heat capacity and damaged the pump bearings or impeller assembly. So if you reset the pump and water pressure is restored but the pump later begins to run continuously you'll have to lower the cut-out pressure until you've diagnosed the problem and perhaps replaced the damaged parts.

These articles should help:

A second possibility is that sometimes when we start pumping water out of a well faster than before we can exceed the well's flow rate (especially if the well is not very deep- doesn't have a big static head). Even if the well later recovers, we can lose prime and lose water pressure, or in some cases run the pump dry and damage it.

Sorry about the bad news, but those are the worries that occur to me from your description.


Thanks for the reply Dan,

The pump is working fine now, the following morning after my post I replaced the thermal protection device, turned on the pump and it immediately started pumping and has been running fine since. Just for clarification and as I explained in my original post, the pump is cycling properly (cutting in and out) with the higher presser setting of 40~60 psi.

I suspect the problem occurred due to my extended continuous use of water while I was working on a landscaping project which had the water running continuously for 8 plus hours. It appears the thermal protection device which is designed to protect the pump from burning out did its job.

Happy to report the pump and well are working great.


Thanks John M - I will add "replace the thermal protection device" to our list of diagnostic suggestions when a pump motor won't run. Can you send along photos of the parts and pump? Use the CONTACT link found at page top, left, bottom.


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