Water pressure regulator (C) Daniel Friedman Varying Building Water Pressure FAQs
Questions & answers about the cause & cure of varying building water pressure & flow

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Water pressure or flow rate variation FAQs:

This article provides questions and answers about the causes of variation in building water pressure for homes connected to municipal or community water supply.

Here are FAQs on the causes & cures for variation in water pressure or water pressure regulation in buildings. In this article series process of water pressure problem diagnosis and the costs of the repair are explained.

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FAQs About Variation in Building Water Pressure

Photograph of a water pressure regulator on municipal water supply

Question: Water pressure varies while taking a shower; sometimes the warm shower gets too cold

I get a noticeable water flow variation, especially during a shower. When the well pump kicks in it over powers the hot water significantly making a warm shower cold. Any ideas what I should do?

Reply: Regulating water temperature at the shower during normal pump operating cycles

If your hot water runs too cool when the water pump turns I suspect that your hot water piping or hot water source is clogged - perhaps if you are using a tankless coil that is mineral clogged this would be more likely.

You could install an automatic mixing valve right at the shower - that valve is designed to keep water temperature constant; first try partly closing the individual cold water shutoff valve for your bathroom - by this I mean a valve in the cold water line that is "ahead" of or before the shower itself. By restricting the cold water flow rate in the piping you may improve the pressure balance.

But overall I suspect the problem is more likely to be clogging in the hot water piping or hot water supply system. That's because the PRESSURE produced by the pump is the same at both hot and cold water piping. It's the FLOW through piping systems that is more likely to vary. A similar effect is found when you're in the shower and someone flushes a toilet or turns on cold water at a nearby sink - and you are suddenly scalded.

If you think your hot water piping is clogged see CLOGGED SUPPLY PIPES, HOT WATER.

It is normal for building water pressure to vary between 20-40 psi or 30-50 psi depending on how your pump pressure control switch is set. Even after you've de-clogged your hot water supply you can make a still better improvement in regulating water temperature at the shower by installing an anti-scald device or valve, either at the hot water source or right in the bathroom at the fixture.

See ANTI-SCALD VALVES for details.

Question: our water pressure comes on fast but quickly drops off to nothing. Is this a clogged pipe problem?

OMG my farm house was built before christ and my pressure gauge on my well has 60 psi works fine except I don't have any pressure in the house, I can turn on a faucet and it fast then drizzles down to nothing and if the kitchen sink is running there is next to none in bathroom, if filling washing machnine there is no water upstairs untill the washer fills up. takes at least 5-7 minutes for toilet to fill and 20 for the tub. How can I get the rust out of my pipes w/o tearing the house apart. I believe that they are clogged with rust since it is hard well water. - Lisa


Lisa if you have no actual water pressure but the gauge is reading showing pressure is present, and provided no one closed a water valve between tank and house, I suspect that the gauge pressure reading is wrong and the gauge is stuck. Try tapping on the pressure gauge to see if it moves.

The same crud that clogs the valve can clog the pressure sensing switch and interfere with proper well pump operation. If it's a rust and sediment problem your plumber might install a filter ahead of the rest of the water equipment.

Take a look at CLOGGED SUPPLY PIPING, but because the water pressure falls off quickly you'll also want to be sure that the water pressure tank is not waterlogged, causing the well pump to have to turn on and off too frequently. See WATER PUMP SHORT CYCLING to diagnose well pump short cycling and water pressure that rapidly rises and falls.

If on the other hand water pressure falls off and takes a long time to recover, I suspect that the well itself is running out of water. For that problem see WELL FLOW RATE and also how to measure the WELL FLOW RATE.


Thank you Mr. Friedman I will certainly try that with a light touch upon looking into the well I saw a capusule looking clear plastic part rustly what is that called and maybe that needs to be replaced I posted this alittle while ago and it didn't show up I turned all water off waited opened all faucets turn back on and no water b/c all faucets were open left only kitchen and water hardly any rust or air not like it use to when we hard power failure as no lights no water. Thank you for helping me, Lisa

Question: high water pressure, varying pressure, & burst components led to a leak

5/19/15 LB said:

All while back I had a problem with my water line bursting at my water meter. It happened on a day when the municipality had turned off the main water to all the rural area. When the water was turned back on, my line burst. I checked my water pressure at the meter and it is 102 PSI. Is that within a reasonable range? I also have a regulator in my home that was installed prior to me purchasing the property. From what I can gather, the previous owners had problems with seals and valves blowing, hence the regulator.

(May 20, 2014) Dale said:

I am on a municipal system with a pressure reducing valve in line. Most of the time the pressure gauge on the house plumbing lines would read 50-60 psi, however I had a problem with the water pressure creeping up to over 100 psi. Simply turning on the water for a few seconds would drop the pressure back down. Looking at the gauge later it could be normal or over 100 psi. I changed the pressure regulator with a new one and it's doing the same thing again. Any suggestions?


Indeed 102 psi is quite high and would be expected to give recurrent leaks at fixtures inside a building IF the building's water pressure regulator was not working or was not properly adjusted.

Watts corporation as well as other manufacturers produce a wide range of pressure reducing & regulating valves.
Usually a "direct acting" pressure regulator is what's installed in homes.

For high pressure commercial operations one might need to install a pilot-operated pressure regulator but in a private home that has very high incoming or widely varying water pressure it's more likely that a 2-stage pressure reduction that I will cite below is what's needed. describes these products from which I paraphrase or adapt:

Direct acting valves, the more popular type of a water pressure reducing valves, consist of globe-type bodies with a spring-loaded, heat-resistant diaphragm connected to the outlet of the valve that acts upon a spring. This spring holds a pre-set tension on the valve seat installed with a pressure equalizing mechanism for precise water pressure control. - retrieved 5/19/15, reference source

You certainly need a pressure reducing valve that can handle the pressure range your municipality delivers, which might mean installing two valves in series - a two-stage, "serial reduction" pressure reduction system. You don't
usually need two stages unless the incoming water pressure varies and is sometimes at 200 psi or higher.

In sum, I suspect the problem is that the original pressure reducing valve you had installed was either improperly selected, adjusted, or perhaps it just failed.

Question: poor shower pressure

(Oct 22, 2014) doug said:

i have a private well tyhat was installed in 1998, it has started recently having good pressure then dropping off almost to nothing then jumping back up. this just started

(Nov 10, 2014) Steve said:

My water pressure is low in the shower until I turn on another device. If I turn on one of the sinks in my bathroom the pressure in the shower goes up and back to how it used to be.
Any ideas? I have a fancy valve from Kohler but that was ruled out. I have 2 other heads in there and it acts the same even without the main. 2 plumbers can't figure it out...Help!


Russ I see a question from Steve - is Russ = Steve?

Low shower pressure: if that's the only fixture suffering - start by removing the shower head and checking the flow. If flow is good clean or replace the shower head. If flow is poor there is a blockage in the line to the shower or one of its valves.

When turning on another fixture improves water pressure I can but infer that the added flow turned on the pump.


12/1/2014 John Schult said:

Replaced pressure switch (40-60) Added 38psi air engaged new switch ran for 15 seconds then stopped. Waited 1 1/2 minutes re-engaged power did same thing will not run complete cycle. ?


Sounds as if the tank is water-logged or water is not able to enter the tank. Or the tank was simply nearly full. Try running some water in the building.

Question: at high water flow pump does not come on to re-fill the pressure tank

(June 27, 2015) Larry said:
Most of the time the system works fine, but there is one spigot outside the pump house that has very high flow, and the switch fails to come on and re fill the pressure tank. I could live with that, but it also happens almost everytime i run my washing machine in the house... Then it's out to the pump to manually make it start.


Odd. I'd check for a debris-clogged pressure switch that is not working reliably

Question: filling the pool drained our water tank and now takes a long time to re-fill

(Aug 18, 2015) Wendy said:
I have a brand new well and pressure pump. It has been filling my 5000 gallon tank with no issues. Then I decided to fill up my pool.
I thought that if I was filling the tanks at the same time it would replenish what I was using to fill the pool but in fact it drained the 5000 gallon tank so I stopped filling my pool. Since this occurred my 5000 gallon tanks take much much much longer to fill. Why did the filling time change after trying to fill my pool? Did I somehow affect my pressure tank?


Wendy, filling a swimming pool OR a 5000 gallon water storage tank takes an enormous amount of water out of your private well.

When I find a home with a 5000 gallon water storage tank it's a safe bet that someone put in the huge tank to try to compensate for a well with a very poor flow rate or recovery rate. The strategy is that we'll fill the big tank very slowly, without exhausting the well, but the big tank will always give plenty of water on demand in the building.

When you try filling the pool from the well you are probably exhausting the well. Exausting the well may have also worn or damaged the well pump.

Check the pump condition, impellers, bearings, motor, current draw; check the well flow rate and water level.

And if you are trying to both fill the pool and fill the big water tank at the same time you're doubling the chances that you will exhaust the well and burn up the pump.

Question: water pressure became intermittent

(Aug 25, 2015) Marg said:
Have had a submersible pump in the lake for the last 8 years. Recently pressure has been intermittent - fast and slow (in and out) to all taps and toilets in the house. It has been suggested it might be the bladder. How do we fix?


In the article WATER PRESSURE VARIATION CAUSES in the paragraph

If the "short cycle" is very short, clicking on and off, there could be a different problem with the pump control pressure switch or with a dirty, clogged water filter if one is installed on the system. Dirty water filters as a source of rapid pump on-off cycling are discussed

you'll see that CAUSES of SHORT CYCLING is a live link that includes how to re-charge the lost air in the pressure tank;

Or at More Reading above you'll find

wherin you can find all of the articles on how to repair or re-charge a water pressure tank's air


Question: why is pump still running at 56 psi

(Sept 19, 2015) sarah said:
have a problem with water pump. water pressure is good 56 water come out good. but why the pump still running when the meter already reached 56?


Chances are the pump is unable to reach the cut-off pressure set on the pressure control switch. Try lowering the cut-out pressure but beware that there may be a failing well or pump.

Question: How do you increase the water pressure

(Oct 18, 2015) Anonymous said:
How do you increase the water pressure. It was doing fine, now havr little more than a stream coming into bathroo




(May 7, 2016) Jeff said:
Let me start bought my 1st house about 2 months ago every since when we use the water the pump goes on off in rapid succession and when I shower the water just stops flowing for a few minutes then starts back up!

Almost like no reserve in the tank I also know that the tank itself shouldn't hold but about 28psi! The other gauge reads like 90-100psi how would I if needed to change this? I know there is something wrong with this water tank somewhere just gotta fix it and hope it's not the submersible!


Very rapid on-off cycling of the water pump suggests that the tank is waterlogged. Search for WELL PUMP SHORT CYCLING CAUSES to read details about cause and cure.


Question: very slow water flow rate due to a water filtration system

(May 19, 2016) Rajesh said:
I've installed pressure tank with only one in & outlet. Right now it's set at 2.5 but due to filteration system, the water level is very slow. How much water pressure to increase maximum.



If the water filter is a cartridge type system, install a new clean cartridge filter.

If that makes no difference, test water flow with no cartridge in the water filter canister.

If that makes no difference there is a partly closed valve, clogged water pipe, or pressure control swtich problem, or the well itself may be out of water.

Question: no water pressure after thunderstorm, thinking of replacing the switch

(Aug 18, 2015) Joshua k said:
I really could use some assistance. We had a little thunder storm rumble through this evening. I didn't hear any thunder pop near my home. Or any tell tale bright flashes or a Power flicker. Went to get some water from the tap and no water. I check the breakers they were on. Check the lil pump house no pressure. For the time being I've shut power off to pump and water heater. I'm thinking to replace pressure switch first. I just replaced the darn pump a year or so ago.


If you have power to the pressure control switch but it's not turning on the pump I'd try replacing the switch. Beware that lightning strikes can damage pump, pump wiring, pump controls, piping, well casing, etc.

Reader follow-up:

Just wanted to say that it was the pressure switch. Turns out that it was not building any at all.

(mod) said:
Thanks for the follow-up, Joshua. That will assist other readers. Often the pressure control switch fails in one of two modes: debris-clogging of the pressure sensor tube or port, or contacts burned.

Question: water pressure doesn't get above 30 psi but pump builds to 60 psi?

(Sept 13, 2015) Dan said:

My pressurizes to 30 PSI. I have a 220V 4 inch well. when I cycle the cut off switch, the pump appears to kick in at 220V which it is designed. It then builds pressure at a normal rate to 60PSI. I changed the pressure switch and the cut off switch. I also checked pressure in the tanks ( I have two) and brought them up to 38PSI with a cut in at 40PSI. Now most of the time it works fine however at least twice a day I hear the pump running what appears to be on 110 and have the issue.

Something I noticed is one of the tanks appears to be empty even with the correct pressure set. also the points will chatter once when I have to cycle it to get the pump what appears back to running on 220V. I am baffled. Help



It sounds to me like a wiring or measurement error. If a 240V motor is wired to run on 240V, for most pumps we'd expect it not to run at all if one of the hot legs is not delivering power.

Check the input voltage and wiring.

An empty pressure tank could be a collapsed or stuck bladder.


Continue reading at WATER PRESSURE VARIATION CAUSES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see WATER PUMP PRESSURE CONTROL ADJUSTMENT - private pump & well pressure controls

Or see WATER PRESSURE REGULATOR ADJUSTMENT - municipal water supply pressure

Or see these articles

Water Pressure & Water Pump Diagnosis & Repair

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