Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER CONSERVATION MEASURES
WATER CONTAMINANT LEVELS
WATER FILTERS, HOME USE
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMP SHORT CYCLING
WATER SOFTENERS & CONDITIONERS
WATER TANK REPAIR PROCEDURES
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL CHLORINATION & DISINFECTION
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
Short cycling water pumps: well pump turns on and off rapidly or too often: this article defines short cycling or rapid cycling well pumps and the various causes and cures for that problem. We explain why rapid on-off switching of the water pump can be harmful and how it also affects building water pressure.
We explain that often sort cycling indicates the need for air in a water pressure tank. In companion articles we explain several ways to add air to a building water pressure tank, and how to detect and correct air and water leaks in a building water supply system where a private well is the water source. We also discuss how to adjust the building water pressure by setting the cut-in and cut-out pressure on the pump pressure control switch.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
What is water pump short cycling? - short cycling of the water pressure tank and why can it be harmful?
Several alternative procedures for adding air to a water pressure tank are described below along with advice about what to do when things go wrong, such as finding air and water leaks. The illustration at page top is courtesy of Carson Dunlop, Inc. in Toronto.
Short cycling of a water pump means that the water pump or "well pump" turns on and off too rapidly or too frequently when water is being run in the building. "Short cycling" means switching on and off every 30 seconds or less. Extreme water pump short cycling may occur every second or less and means you should turn off the pump system to avoid damaging the pump or controls.
If this is the problem with your water pump, SHORT CYCLING CAUSES describes the most common causes of this problem.
We also provide a complete SHORT CYCLING DIAGNOSIS TABLE that lists all possible causes of well pump rapid cycling on and off.
If you are not sure what "water pump short cycling" means or how it is recognized, read SHORT CYCLING WATER PUMP.
Intermittent water pump cycling which is discussed at INTERMITTENT WATER PUMP CYCLING means that the water pump comes on for no apparent reason.
Loss of water pressure means that the pressure with which water enters a plumbing fixture has become too slow, or is sometimes too slow or weak in water flow rate, or water flow may stop entirely. See WATER PRESSURE LOSS DIAGNOSIS & REPAIR
The "water storage tank" is doing more than storing water. Its air charge acts like a spring to smooth the delivery of water in the building. If the building water supply pump is "short cycling" - coming on and off rapidly, you may need to add air to the water pressure tank.
This step is important to protect your private pump and well from damage due to short-cycling due to loss of air in the pressure tank. Short cycling of the pump motor can burn up the pump relay control.
The minimum that a building owner or occupant needs to know is that short cycling is an on-off cycle of the water pump in a house with a private water pump and water supply well system. The "short cycling" water pump is turning on and off rapidly, perhaps every 10 to 20 seconds or even more frequently. Water pump short cycling can damage the pump or controls. Repair is needed at one or more of: the water pressure tank, water pump pressure control switch, water pump, water filter, or the well or building water supply piping. If you are not interested in tackling this easy repair yourself, call a plumber.
The sketch shown at the top of This article shows the components of a typical residential water well, water pump, water pressure tank, and water pump control system. Below we include other drawings and photographs of wells, water tanks, and their associated valves and controls.
At some properties the well pump may be inside rather than in the well as in this drawing, and on your tank the water pressure gauge may be mounted on a special air volume control fitting on the back of the water tank itself rather than as shown in this sketch. Sometimes people think this water tank is to "store" water for use in the building. That's rarely the case. Usually water is "stored" by being present in the well and in the ground around the well.
If a pump-operated water supply system is turning on and off rapidly (every few seconds) it would be smart to turn off the water or turn off electric power to the water pump and call a plumber promptly.
If your water pump comes on at odd times but is not short-cycling, see INTERMITTENT CYCLING WATER PUMPS.
Normally the "pump on" cycle is 30 seconds to 90 seconds or longer, depending on water tank size, and the "pump off" cycle is the same or longer.
What is Water Pump or Water Tank "Short Cycling" - rapid on and off water pump
Short cycling of the water pump means that the water pump keeps turning on and off rapidly whenever you're running water at one or more fixtures in the building. The pump on-off cycle may be perhaps every few seconds, or perhaps every 10-20 seconds. This is a problem, which we diagnose, discuss, and for which we offer repair procedures below. The minimum that a building owner or occupant needs to know is that short cycling can damage the pump or controls, and that action is needed.
These short cycling problems happen with both in-building jet pumps and with in-well submersible pumps. It's trickier to notice a short cycling submersible pump since you won't hear the pump motor, but you will hear the pump relay clicking on and off, or you can see the water pressure gauge cycling up and down rapidly.
If you are not interested in tackling this easy repair yourself, call a plumber. If the system is turning on and off rapidly (every few seconds) it would be smart to turn off the water or pump and call a plumber promptly since if you let this problem continue you're likely to damage a pump control or pump motor (expensive).
You can tell if your water pump system is "short cycling if:
If you don't know how to find your pump pressure gauge, pressure controls, switches and controls, see WATER PUMP & TANK CONTROLS & SWITCHES
How to Detect a Short Cycling Water Pump and Tank
We give more description of how to detect short cycling of the water pump at SIGNS OF AIR LOSS
How to Diagnose the Cause of a Well Pump that Keeps Turning On and Off
Watch out: before "fixing" a short-cycling well pump, you'll want to try for an accurate diagnosis of its cause - the right fix is cheaper than a whole collection of wrong fixes.
See SHORT CYCLING CAUSES for an explanation of the most common causes of well pump short cycling
See SHORT CYCLING DIAGNOSIS TABLE for a table that lists the all of the possible causes of well pump short cycling
If it turns out that you want to just try the easy, quick, above-ground "fix" of adding air to the water tank, we describe how to correct water pump short cycling, in great detail and giving several methods, at WATER TANK AIR, HOW TO ADD for conventional water tanks that do not use an internal bladder.
Bladderless water pressure tanks, because the air charge and water are in the same container, can lose their air charge over time (air is absorbed into the water) and may need air added.
At BLADDERLESS STEEL WATER PRESSURE TANKS we discuss waterlogged water tanks and well pump short cycling.
See WATER TANK AIR, HOW TO ADD for details on how to add air to a water pressure tank.
At WHAT GOES WRONG WITH an INTERNAL BLADDER TYPE WATER TANK? we discuss the combination of well pump short cycling and a burst water tank bladder and how this condition is identified and repaired.
See this detailed article on bladder-type "captive air" water tank diagnosis and repair:
Question: should I replace my old water tank?
We just had our pump replaced after 18 years. Total cost with tax was $2400. Project was done on emergency basis on a Friday night and we were really stuck. During his visit the plumber/owner suggested we consider a larger pressure tank than our 20 gallon unit, also recently replaced. The system worked well for many years and I don't see the need to purchase another larger tank. Any thoughts? - Wayne Ouellette
Reply: maybe not.
If your water tank is a newer bladder type, even a smaller 20-gallon tank gives the equivalent of a larger old style (non-bladder) tank in the draw-down cycle - the amount of time that you can run the water before the pump has to come on.
As long as your pump is not WATER PUMP SHORT CYCLING (which may shorten pump life), the gain from a larger tank is probably not much. If your tank is an older type with no internal bladder, the reason to go to a newer tank would be reliability and reduced maintenance.
Some Reasons to Consider a New Water Tank
Watch out: before you go to the trouble and expense of replacing a water pressure tank, make sure that you have correctly diagnosed the problem that you are "curing" - you wouldn't want to replace a water tank only to find that you still have the water pressure or quantity problem because another, perhaps less costly, part was at fault.
Continue reading at SHORT CYCLING CAUSES or select a topic from the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs) about Short Cycling Water Pumps
Question: Drastic water pump short cycling every 3-4 seconds, sometimes pump won't come on at all, loss of house water pressure
Mark said: Ok so I have a few problems here. First off my pump is short cycling drastically as in I flush my toilet and within 3-4 seconds I hear the pump kick on. Second, when it kicks on it only stays on for a few seconds before turning off then it only stays off for a couple more seconds before turning back on. And recently about once a day or once every couple days the pump wont come on at all and I have to go down and tap the pressure control switch housing for it to come on. By the time I realize that, we have pretty much lost all pressure in the house due to normal use.
I haven't quite nailed down any tying reasons or times when this happens like my wife doing laundry or something along those lines. When the pump is working we have plenty of pressure, almost too much (water sprays out hard and makes a mess when doing dishes - "lol"). I have looked through this site and have found a bunch of useful information but am overwhelmed and don't have a clue where to start. Any guidance in this matter would be greatly appreciated. - Mark
(Jan 27, 2013) Hunter said: We have a cistern filled by city water and a submersible pump which pumps to a bladder tank, which supplies the house with pressured water. The water flow from faucets has began to pulse so inspected the pump setup outside and observed the pump shorty cycling. I purchased and installed a new pressure switch thinking it would be a cheap,easy repair, but afterwards, the pump continued to switch on and off, every second. Does this sound like something is clogged?
(Apr 2, 2014) firstclasslimo said: My pump keeps cycling every 1/2 second for about 10 to 15 pulses( on/off/on/off etc.)when it reaches its cut out set at 58lbs psi.with a differential set at aprox. 63 to 65 psi. I can't find a happy medium to shut this thing off. When it does shut off, pressure is stable with no loss,that is IF all faucets are closed: but if shower or faucet is running;the pump won't shut off. I have a new pressure tank with bladder, new pressure switch, new pressure gauge(0/100 range).What do I do? Not sure if i have any valves like a check valve or foot valve etc.installed. Should I ? This is not a new system it used to work fine then started acting up,so i replaced pressure switch as contacts were carboned bad. Didn't fix. Now I can't get thing set right.
Reply: Your pump is rapidly short-cycling and may be overheating, this can lead to a submersible pump motor going off entirely then back on under control of a built-in thermal overload switch
Mark and Hunter:
You are describing a classic well pump rapid short cycling problem. Eventually that condition can actually damage the well pump, resulting in less water pressure and flow than previously. You should be able to obtain satisfactory water pressure with the factory settings of your pressure control switch, typically 20/40 or 30/50 cut-in/cut-out.
Mark I suspect that the reason you sometimes lose all water pressure under these conditions is that the rapid on-off cycling of the water pump is contributing to an overheating pump motor. Many electric motors include an internal thermal overload switch. When the motor is too hot, the switch turns off the motor. Later when the motor cools down on its own, the thermal reset switch resets and the pump will run again.
The rapid on-off short cycling well pump may also have led to burning on the contacts of the pressure control switch. That's why sometimes you have to tap the switch to get the pump to run. There could be other pressure control switch problems such as clogging of its pressure sensor due to debris in the water line.
My best advice about diagnosing short cycling is in the article above. I'm not sure just what's going on in the case you describe but I've seen similar problems with a blocked or dirty water filter, mostly-closed water shutoff valve, or a dirt-clogged pressure control switch sensor.
The stable pressure with pump off argues against a leaky foot valve or piping leak. I don't rule out a sticky check valve or foot valve intake but I'd start with the other items I listed first.
Question: Short cycling well pump, bad pressure settings or bad check valve?
I think my check valve is bad, letting air back to well. Our well pump runs for 3 seconds shuts off for 3 seconds. It does this over and over. I am thinking pressure settings on bladder tank might not be right? - Tim.
Reply: Check for a bad snifter valve and/or a water-logged pressure tank
Before trying to change the pressure settings at the pressure control switch, you should check for a water-logged water pressure tank or another cause of well pump short cycling.
Take a look at the article SHORT CYCLING WATER PUMP - usually the first thing to check is loss of air in the pressure tank; it's true that a bad foot valve or check valve that causes water to bleed back into the well (and thus the tank pressure to drop) can cause the well pump to cycle more often, but that alone wouldn't get us to cycling every 3 seconds. That's more likely a lost air charge or a clog that is not letting the pump get water into the pressure tank;
Also, if your well uses a submersible pump and a water tank that does NOT use an internal bladder, your system may include a snifter valve that is supposed to be letting air into the well piping - as a means of keeping the air charge in the water tank. If the snifter valve has failed (as they can by debris clogging) that could explain a waterlogged pressure tank and a short cycling well pump.
Comment: Draining the water tank, adding air, and adjusting the pressure control switch solved the short cycling water pump problem
Problem: Pump cycling every few minutes for months....Your question and answers solved my bladder type pressure tank cycling problem. I drained the tank and added air to 28 psi (was below 20 psi). I filled/pressurized tank and adjusted limits to 30 (low) and 50 (high). And WOW, now it takes 5 toilet flushings before pump kicks on.
I tested the pressure tank psi after pump clicked off and my gauge read 53 psi. So my problem was low air in the pressure tank and limits out of adjustment. Thanks for your instructions that anyone can follow and it saved me lots of money for a plumber.
Bob: Thanks for the nice note; we work hard to make our information useful and unbiased; I'm thrilled it worked for you; we continue to welcome questions or suggestions for our content as together we're smarter than working alone.
Question: My water pressure drops too quickly and reaches cut-out again too quickly
I have a submersible pump and a bladder pressure tank. I have the cut in at 30 and the cut out at 50. My well seem to a lot. If I watch the gauge when pressure hits 30 the pump turns on until it hits 50, but it take only a few seconds for the pump to drop back down to 30, this is with just running a faucet. Should it be cycling that fast? - Robert 7/7/2011
(Oct 23, 2012) Lori said: My water pump/tank turns off and on every 1 min 38 seconds and I hear a brief water trickle in the tank. This is when no water is running in the house. Is that low air in the tank too? or a hole in the bladder?
(Jan 20, 2013) David said: our system is extremely noisy at night. there is a continuous 'clunk clunk' every few minutes, like the system wants to come on, but changes it's mind. there is no water being used. help, my wife can't sleep.
(Oct 31, 2012) Sue said: We can hear the short cycling and what we've noticed is the pressure gauge does not move at all. Is this the problem?
(Dec 17, 2012) Anonymous said: HELP My pump comes on with every flush, is that normal?
Reply: How to tell the difference between water pressure tank is waterlogged, a leak or running water problem, and a clogged pressure control switch sensor port
Question: possible failed water pressure tank internal bladder
So have a air leak some where. Refilled pressure tank up to 28lbs today and did a soap test around valve stem and see no apparent leaks. So I leaning to having to replace the bladder. Its just over 10 years old, I read they hardly ever go bad. I would like to know your thoughts. ( since filling with air pump cycles normally) - Anon 7/9/12
Indeed from reports here tank bladders do fail on occasion; in some water tank designs the bladder can be replaced without replacing the entire tank assembly.
Yes I have read in numerous places that they can fail. This one is 11 years old, have one on order and hope it solves the problem. - Robert Lee
Question: well short cycles but the tank pressure reads 50 psi
My well has been short cycling recently so I checked the tank pressure. It reads 50 psi. Wondering what is the cause. Could it still be waterlogged tank? - Chris 11/18/2011
indeed in a waterlogged tank the pressure will still go up to the cutoff point - but you'll see a very short drawdown time from when you turn on water in the building to when the pump has to turn back on - that's "short cycling" as we describe above.
Question: well pump loses pressure too quickly when water is taken from the system - drops in 10 seconds
My well pump seems to lose pressure (cut in?) too quickly when water is drawn from the well system. When the water is turned on the pressure drops from 60 PSI to 40 PSI within 10 seconds. Once the system reaches 40 PSI the switch is activated & pressure is restored within a minute of the water being turned off. I believe that I have a tank with a bladder (it an Amtrol tank) & I've tested the pressure of the tank when the well system is active (it reads 38 PSI).
I've also tested the pressure after cutting the power to the system & draining the tank (0 PSI). I'm not sure why my tanks loses pressure so quickly & i'm afraid the well motor will burn out soon if this is not corrected. Is this an issue involving the thank bladder? Any advice? - Anon 3/5/2012
I'm assuming this is a slow leak & is what caused the drop in pressure (I recently purchased the home where the well is located). Any ideas for correcting this issue? I'm going to research it now, but would like to avoid buying a new tank if possible. In the meantime, i guess my only fix it to monitor the tank pressure & recharge as needed.
Question: when I attach a nozzle or sprinkler to garden hose the well pump no longer runs continuously
My shallow water pump runs just fine with a hose attached with no increased back pressure, but if I attach a nozzle or a sprinkler to the end of the hose, the pump will run for 30 seconds and then shut off. It cycles like that continuously. I have tried increasing and decreasing the air pressure in the bladder to different levels and it does not seem to correct the problem. How do I know the correct air pressure? It is not written anywhere on the pump or the valve. Any other suggestions? - Dr. Louis Gotthelf 9/26/2012
When you attach the hose nozzle you are still running water pretty fast, but not quite so fast, so you draw down the water in the tank and the pump will cycle on and off as needed; Just be sure the tank has adequate air charge - that 30 seconds may be a bit short, depending on the size (volume) of your pressure tank.
Question: water pump turns on and off a lot, and water temperature in the shower then fluctuates
I have a water pump that seems to turn off and on a lot when we run water, especially in the shower. When the pump turns on, our water temperatures fluctuate. We thought it was the water heater so we replaced that. Water temperatures appear better but the fluctuation is still there. We do have a leaking water hose connection outside of our home but just drips.
Could that explain the water pump running a lot? Since replacing our water heater we also lost some of our water pressure on the hot water, cold water is fine. Can you explain what could be causing the temperatures to fluctuate when the water pump turns on? Our water source is spring fed if that helps at all. Thanks! - Jennifer Beckler 10/3/2012
Question: pump is slow to reach final cut-off pressure - not short-cycling
(Mar 3, 2014) Rich Maltese said:
I just replaced a pressure switch, tank and gauge. The pump starts at 30#'s and runs a few minutes to get to 48#'s, then it seems to take a few more minutes at least to get to 50#'s and shut off! even with water off. Is this normal, or do I need to adjust the pressure switch? The pressure in the tank I was set to 26#'s before filling it with water.
Rich, it's not unusual for the pump to run longer at the very end of the pressure range if it's an older weaker unit or if the water supply in the well is limited. But yeah, if you can get to 48# quickly, I'd try dropping the CUTOUT down that 2 psi - it'll save work on the pump.
The tank pressure when water has run (and pump is off) until there's no pressure in the tank, should be set at 2 psi BELOW the cut-in pressure.
Rich this is not a short-cycling rapid pump on-off problem. But In the case you describe, when the pump runs for minutes or longer to get from 48psi to 50 psi, and presuming it's filling a typical not a very large water pressure tank, then you may be operating the pump cut-off pressure at near the edge of what the water pump is capable of achieving.
This symptom can occur due to a worn or damaged pump impeller or low voltage or a damaged pump motor. More subtle, a leak in the well piping might also contribute to this symptom.
Question: surging water pressure
(Jan 20, 2013) Sam said:
We are in the process of changing the water pressure tank. I noticed yesterday that when running water we would get a blast of strong water then it would go back to normal. It does seem to be waterlogged. Would this cause it or do we have a bigger problem with our submersible well pump?
Sam, I suspect that you are seeing the surge in pressure when the water pump is running, and the more modest pressure when water is being delivered by air pressure in the water pressure tank. I'd start by draining the tank and making sure it had a proper air charge. Keep me posted
Question: Pump runs 60 sconds on toilet flush but runs continuously with other uses
(May 5, 2014) H20 said:
when we flush the toilet or Use the kitchen Faucet the pumps runs for exactly 60 seconds but when we used the washing machine or Take a shower it runs continuously or until the water is turned off then it runs a Min longer before shutting off . i have a 2hr starite on a 30 gallon flotech.
When your system is drawing water at a fast enough rate the pump will run continuously and flow rate will be ultimately the pump's capacity.
When your system is drawing water at less than the pump's total output capacity the pump will "get ahead" and will be able to raise pressure in the system to the cut-off point set in the pressure control switch.
Check your tank and pump frequency to decide if it's short cycling - as described in the article above.
Question: pump & water pressure drops to weak then comes back - water pressure comes and goes
(4/28/2014) Eric Sekeres said: so here is my problem. In the last week my irrigation system was doing weird things. I turn it on and the water comes out full strength. Then water pressure drops to very little and then comes back. Is it a bad valve or bladder or some other problem. My neighbors have full water pressure so I think the aquifer is strong. Need help. I'm handy but when it comes to sprinklers I am the village love. Any help is appreciated.
Reply: this is not short cycling of the pump it's a loss then return of water pressure.
Eric you describe water pressure that "comes and goes" - a problem we discuss and diagnose in a related article. Please see
Since you think there is no problem with the well flow rate itself, I'm guessing your pressure control switch sensor port is clogged but it could be something else.
Question: short cycling well pump, very short on cycles, no pressure tank
5/18/2014 ohwell said:
i had a house fire 2 years ago..well pump has not run since today..i had my well pump directly wired from the temp power pole to the pump feeding a wellstand..pump goes on and off at 10 second intervals ..i can hear it down the well pipe..water will run sometimes as the pump cuts in..well is 100' deep..water was brown at first and seemed to be strong untill pump started cutting out..did well pump sit to long??
It sounds as if your pump is short cycling for one of the rasons discussed in the article above. Take a look at the "More Reading" articles listed above and try one of these two diagnostic articles
SHORT CYCLING CAUSE: WELL PIPE LEAKS
i discovered today the pump comes on for about 4 seconds full blast and then cuts out for approximately 40 seconds then repeats..i have 30 amp breaker on it..theres no pressure tank..system was configured for a pressure system..im in the process of rebuilding and just wanted to have water for my RV on construction site..i have a simple plug for a switch to turn the well pump on and off..will read the topics you suggested..thanks
after reading the links above im still at a loss still for the reasons ive explained..the system was perfect before the fire..i cut excisting hose shorter in case of blockage and moved the water line over to the side of the property where i put an 8' wellstand 4'up/down..i have a call into the local guy here..its the long weekend still..i will give him a call again tommorow
Reply: no pressure tank?
You are describing short cycling; I'd be quite interested if we've come up with another cause that's not been cataloged.
When a water pump is "on" for only 4 seconds I suspect that it's pressurizing the system to the pressure switch's cut-off pressure too quickly. Typically that's caused by
On odd occasions pump behaviour such as you describe could be caused by debris clogging the pressure sensing port on the switch.
When there is NO pressure tank, as in your system, it'd make sense that the pump would run only for seconds before reaching the cutoff limit.
Short cycling the pump risks burning it up.
Questions & answers or comments about diagnosing and repairing a short-cycling well pump: how to fix a well pump that keeps turning on and off too frequently
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References