How to diagnose loss of water pressure that later improves or returns "on its own"
When you lose water for some time period but later it returns we think immediately of the following possible explanations. This article describes common water pressure-loss problems and their causes, and provides links to more-detailed diagnosis and repair articles for each of those situations.
The well is being pumped "dry" and you're waiting for the well itself to recover water. With age however some wells deteriorate and deliver less and less water as their flow rate from the water table into the well diminishes. This occurs as minerals clog the cracks or passages through which water is entering the well.
A well may be pumped "dry" - and the pump stops delivering water, or the well may be pumped down to a low flow rate - or a low recovery rate, which in some installations may permit the pump to continue to run but it will deliver water only at a reduced rate.
Low Well Water well pipe tailpieces:
Some wells that are known to have intermittent low water problems may be equipped with a special tailpiece on the water pick-up end of the well pipe precisely to prevent the well pump from becoming damaged when water level in the well drops too low.
The tailpiece permits the in-well water pump to continue to run by recirculating well water within the pump but by halting delivery of water or slowing delivery of water to the building.
See WATER PUMP LIFE EXPECTANCY where we describe these conditions and parts in more detail.
This is a very likely cause of the intermittent loss of water or water pressure symptom.
Well pump motor is overheating: if a well pump motor is overheating for any reason (low voltage, bad start/run capacitor, damaged motor, damaged pump impeller parts, loss of water in the well, pump running dry) it may be a model that will turn itself off when too hot. A thermal sensor inside the pump motor housing handles this job.
With the motor off for a cool-down period, the thermal sensor automatically resets and the pump will run again. Typically the "off" time is 15-20 minutes. If the pump on-off activity is erratic or very long, it could be that the problem is a bad thermal sensor switch.
Note that other electric motors may have a thermal reset switch that is mechanical and "pops out" to show a red "reset button" that must be pushed back in manually. If the motor is still too hot, pushing the button won't work - the button won't stay in. See
A pump is shutting down on thermal overload and you're waiting for it to cool down and automatically re-set its overload switch.
If the well pump is visible in the building you can diagnose this condition:
If the pump keeps running and you have no water there is a problem with the well or well piping or foot valve in the well -- maybe. See contrasting cases after this list.
Or on occasion, the pump could itself be damaged - its motor is spinning but the pump impeller is broken and the pump is not moving water.
Explanation: If the well pump keeps running and you have no water it is also possible that the pump itself is defective, such as having broken internal parts so that the motor runs but the pump does not move water. But if the impeller blades in the pump are broken, the pump may spin but no water is moved inside the pump housing - the water supply system would have poor water pressure or it may have no water and never recover.
By contrast with cases where you lose but then recover water pressure in the building are cases where you lose and do not recover water pressure or flow:
You'd have either no water or only very low pump output no matter what conditions in the well.
Or the pump has lost its prime. If the water tank is empty the pump may need to be primed.
See WELL PUMP PRIMING GUIDE
If the pump is in the well you can't see these conditions directly but an electrician or plumber can do some diagnosis from the building by noting the amperage draw on the pump circuit.
If inside the well there is a leaky or broken water line rising from the pump, the pump could run but deliver less or no water to the building. If this defect is present, the system will not recover to normal operation on its own. In may cases the pump will deliver some water pressure but it is poor.
If the well pipes come disconnected completely, the pump may run but no water will be delivered.
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
Details on how to repair the water pump pressure control switch are discussed
at WATER PUMP PRESSURE SWITCH REPAIRS The illustration at page top is courtesy of Carson Dunlop, Inc. in Toronto.
How to boost water pressure in a building by installing a pressure booster pump and pressure tank is discussed in detail at WATER PRESSURE BOOSTER PUMP
If the building water supply stops and takes minutes to hours to recover,
you may have problem with the well flow rate.
But the problem of lost water supply and pressure could be
more mechanical: a bad well pump.
The well pump, in turn, could have been damaged or hastened to the end of its
life by a bad water pressure tank which has caused well pump short-cycling. Short cycling of the pump motor can burn up
the pump relay control.
Readers of this document should also see WATER TANK REPAIR PROCEDURES how to diagnose the need for air, how to add air,
stop water pump short cycling to avoid damage - water storage water pressure tank safety.
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(June 27, 2011) John said:
I experienced low pressure yesterday that later recovered on its own. The pressure cut in and cut outs on the switch on the pressure tank are at 30 and 50 PSI. Observing the pressure gauge on the tank, the pressure had dropped to only 20 PSI, and would decline to 10 psi (with a tap open to observe) before the pump would come on, but then the pump would cut out shortly afterat perhaps 20 PSI, before reaching 50 psi. (The pump is at the bottom of the well, but I can hear the water in the pipe when it is running.) I thought the switch had somehow lost it's adjustment, so I took the cover off and watched the location of the contacts. Even though the pump wasn't running at 20 PSI, the contacts were closed and, in case the contacts were bad, I measured the voltage in the wires actually going out to the pump, and it showed 240 volts. I didn't run anything for a while and the pressure recovered, but then the problem reoccurred later in the day. I woke up this morning, and the tank showed the full 50 psi, and after I showered without any loss of pressure, the tank showed the full 50 PSI. I don't think it could be the well going dry because my well is pretty deep and it has been a wet summer so far. Any idea what might be happening?
It sounds as if the water level in your well or the well recovery rate had dropped; if it were a piping leak or a control problem I wouldn't expect the water pressure to recover on its own.
(Sept 20, 2012) Mike B said:
My system will run fine for 3 or 4 hours then shut off for about the same amount of time, then run properly for 3 or 4 hours. Not exactly like clockwork, and I've never plotted it. Could be temperature control, I'm guessing, or very slow leak, but I would suspect something in the control circuit, not tank. Any ideas? Thanks
Mike, usually an overheating water pump that goes off on thermal reset will recover much sooner than 3-4 hours, though another reader reported a similar problem that he traced to a bad thermal reset switch in the pump itself.
I'm not sure how a leak would be intermittent.
(Mar 8, 2013) Steve said:
My water pressure fluctuates sometimes.And then sometimes it cuts off completely, but comes back on after a minute.I checked the tank, no water coming out of air/valve stem, just air.
(July 4, 2014) Anonymous said:
I have a well and take a shower in the day and the water will do on then for like 30sec it will stop then come right back what is it
Anon check for a water logged pressure tank and/or a clogged pressure control switch that is not properly sensing changes in water pressure
(July 29, 2014) Anonymous said:
I have an intermittent pressure problem with my well/submerged pump. Every so often (once to three times a day) my pressure drops below 20 PSI; the pump will be running but cannot keep up with normal demand. It remains in this state until I do one of two things. It will be fixed if all water is turned off allowing the pressure to slooowly build up to cutoff. It can also be fixed immediately by cycling the circuit breaker off/on. System has been recently serviced with new controller and new pressure switch. Air tank pressure was also adjusted. Pump is roughly 20 years old.
Anon I think you are describing either a pump that is damaged or has low voltage, or a well running out of water.
(Feb 13, 2015) sue said:
we have a 2 gallon pressure tank on a 40 gallon hot water heater. is it to small? we live in a mobile home the water doesn't have to go only about 7 feet
we just bought a new tank and water heater, we have been burning up capacitors like crazy. now we have no water
Sue what kind of capacitor is used on a water tank and water heater - I'm unclear; but in any case I suspect an electrical wiring error.
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Thanks to reader René A Valencourt, CCP, MCTS,
CTB, Inc. for technical editing 10 Sept 2009.
Smart Tank, Installation Instructions [ copy on file as /water/Smart_Tank_Flexcon.pdf ] - , Flexcon Industries, 300 Pond St., Randolph MA 02368, www.flexconind.com, Tel: 800-527-0030 - web search 07/24/2010, original source: http://www.flexconind.com/pdf/st_install.pdf
Typical Shallow Well One Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Typical Deep Well Two Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Water Fact Sheet #3, Using Low-Yielding Wells [ copy on file as /water/Low_Yield_Wells_Penn_State.pdf ] - , Penn State College of Agricultural Sciences, Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
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