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WINTERIZE A BUILDING
Internal bladder water tank troubleshooting: this article describes the diagnosis and repair of internal bladder type water pressure tanks: how they work, what goes wrong, how to fix it. We explain how internal bladder type water pressure tanks work, what goes wrong, how to diagnose the trouble, and how to repair it.
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Building plumbing fixtures (sinks, toilets, showers, tubs) are supplied with water from the building water supply piping, and drain into the building drain-waste-vent (DWV) system.
How water pressure tanks work
When water is turned on at a fixture in the building, compressed air in the water tank acts like a spring: it pushes water out of the water tank and into the building water supply piping and thus water is sent on to the building plumbing fixtures.
If many fixtures are being run at once in the building, or if the water flow rate produced by the pump and piping and controls is a modest one, the pump may run continuously all while the fixture is being operated.
More typically, if only one fixture is running and if the pump and well can deliver a high water flow rate, the pump may come on and off several times while the fixture is being run.
As water leaves the water tank, water pressure in the water tank drops. Since the water tank also contains air, the air pressure drops too. In the tank water pressure and air pressure will be at the same psi. Sketch courtesy of Carson Dunlop Associates.
A pressure control switch, usually mounted on or near the water tank, senses the pressure drop, and at a pre-set "pump cut-in pressure" (typically 20 or 30 psi) the pressure switch turns on the water pump. See WATER PUMP PRESSURE CONTROL ADJUSTMENT for details of this control.
The water pump, located at the tank or perhaps in the well, pumps water to the building from the well, simultaneously re-pressurizing the water tank and providing water to the building. See WATER PUMP TYPES & LIFE EXPECTANCY for types of water well pumps, how they work, how they are diagnosed and repaired.
Because the water pressure tank is connected to the water pump (water in from the well) and also to the building water supply piping (water out to the building) the water tank is said to be "floated on the water line" and when the water pump is running water is pushed simultaneously into the water pressure tank and into the building supply piping.
The pressure control switch turns off the water pump when water pressure in the pressure tank reaches the "pump cut-out pressure" (typically 40 or 50 psi) - pressure switch turns off the well pump.
Readers of this document should also see WATER TANK BLADDER PRESSURE ADJUSTMENT where we describe adjusting air pressure in a bladder type water tank to factory specs, and also see WATER PUMP REPAIR GUIDE an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost. The illustration at page top is courtesy of Carson Dunlop Associates.
What's the Difference Between a Bladder Type Captive Air Water Tank and a Conventional Steel Bladderless Water Tank
Bladder Type Captive Air Water Tanks
Bladder type or "captive air" water tanks (shown in our photo at left and in the sketch above) store the water tank's air charge in the upper portion of the steel water tank. Water in the tank moves in and out of a rubber bladder in the tank bottom. Because the air charge is kept separate from the water in the tank, air is not absorbed into the water and bladder type water tanks do not normally need to have makeup air added.
On some captive air water tanks this design is reversed. For example on the WellMate™ water tank the water is in the tank and air is in the tank bladder. This difference can confuse the burst water tank bladder diagnosis procedure which we describe below. At WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate we provide separate water tank diagnosis and repair advice.
Water pressure or water pump short cycling problems with bladder-type water tanks are usually traced to a problem with the pump controls, with well and water piping leaks, or less often, to a failure of the internal tank bladder itself - a component that may be replaceable.
If the water-containing rubber bladder in a "captive air" water tank is defective (it can become stuck to itself and remain collapsed), the result can be a rapid on-off short cycling of the water pump. We test water pressure tanks to see if they're empty or nearly empty of water by seeing if we can gently rock or move the tank.
If the water tank is heavy with water it does not move easily. Be careful not to jiggle and break a pipe!
Water pressure tanks, their different types, how to identify them, and their repairs are described just above and in more detail at WATER TANK TYPES.
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.
Traditional no-bladder Steel or Fiberglass Water Tanks
Modern steel bladderless type water tanks may be coated internally to increase the water tank life by resisting corrosion. That's what "glass lined" refers to on some water tanks. (A "glass lined" or "epoxy coated" water tank will not be a bladder type water tank which we discussed above.)
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. See WATER TANK AIR, HOW TO ADD for details.
Bladderless Fiberglass Water Pressure Tanks, such as the WellMate traditional hydro-pneumatic water tank operate similar to the steel water pressure tank, but incorporate a tank-top mounted air volume control and offer the advantage (over steel water tanks) of no risk of rust perforation and leak at the water tank.
At WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate we provide separate water tank diagnosis and repair advice for this water tank type.
Bladderless Fiberglass Water Pressure Tanks, such as the WellMate traditional hydro-pneumatic water tank operate similar to the steel water pressure tank, that is, no internal bladder is used to maintain and separate the tank's air charge and water charge pressure. These tanks incorporate a tank-top mounted air volume control and offer the advantage (over steel water tanks) of no risk of rust perforation and leak at the water tank. At WellMate Diagnosis we provide separate water tank diagnosis and repair advice for this water tank type.
At OLDER STEEL TANKS - Bladder-less Traditional Steel Water Pressure & Water Storage Tanks we discuss this water tank type in detail.
Water pressure or water pump short cycling problems with bladder-type water tanks are usually traced to a problem with the pump controls, with well and water piping leaks, or less often, to a failure of the internal tank bladder itself - a component that may be replaceable.
1. Water tank bladder rupture: if the water containing bladder in a captive air water tank becomes ruptured, torn, or leaky, the result can be a very short water draw-down cycle before the water pump runs,or rapid on-off short cycling of the water pump.
Water from the tank bladder leaks out of the bladder and into the steel tank itself where it replaces more and more of the air charge until finally the behavior of the water system is much as in the water tank bladder collapse discussed just below.
A water tank bladder might rupture from age, an internal defect, or if the pump pressure control switch is defective or is set so high that the water pressure breaks the bladder but this last cause is a bit unusual since the air pressure and water pressure on the two sides of the tank bladder's are normally the same.
2. Water tank bladder collapse: if the water-containing rubber bladder in a "captive air" water tank is defective (it can become stuck to itself and remain collapsed), the result can be a rapid on-off short cycling of the water pump. A stuck tank bladdeprevents water from entering the pressure tank. There will be no appreciable water draw-down quantity and the water tank will remain "light" if gently shaken in place.
Watch out: We check water pressure tanks to see if they're empty or nearly empty of water by seeing if we can gently rock or move the tank. If the tank is heavy with water it does not move easily. If the water pressure tank is empty or nearly so, it will be very light and easy to move. Be careful not to jiggle and break a pipe!
3. Pinhole water tank bladder leak: if the tank's internal bladder has not burst but has a small leak the tank air pressure will increase above standard air charge pressure as water accumulates in the air space - details are below.
Why don't we just look at the water tank pressure gauge to see if there is water in the tank? Well we do. But because debris or other failures can cause a water tank pressure gauge to read pressure even when there is none in the tank (the gauge can get "stuck"), we don't rely on just tank gauge readings. For more about water tank pressure gauges, see WATER PRESSURE GAUGE ACCURACY and see WATER TANK BLADDER PRESSURE ADJUSTMENT.
If the water tank is empty or nearly so, then water is not entering the tank. If the water pump runs but no water is entering the tank, the problem could be a collapsed bladder that is stuck onto itself, not admitting water. There could also be another problem such as a defective water pump, a well line leak, or other cause for water not entering the tank - so you may need to also see WATER PRESSURE LOSS DIAGNOSIS & REPAIR.
If the water tank is "full" or nearly so, then if there is still no water pressure, the tank bladder could be also burst but the tank may have lost its air charge (over time air is absorbed into the water - the burst-bladder water tank is acting like a bladderless water tank discussed just above). In this case you might observe that the well pump (or pump control) is switching rapidly on and off when water is run in the building - see WATER PUMP SHORT CYCLING.
Bladder type or captive-air water pressure tanks and their repairs are described just above and in more detail at WATER TANK TYPES.
How to diagnose a burst water tank bladder
If you remove the cap from the air valve on the top of your water tank and momentarily depress the pin in the center of the schrader valve, normally air will hiss out.
Watch out: Don't keep holding this valve pin down or you'll lose the air charge.
At WellMate Diagnosis we provide separate water tank diagnosis and repair advice for captive-air water tanks in which the air is in the bladder and the water is outside the bladder in the water tank.
Thanks to Jeff Garmel for suggesting text clarification in this discussion of water pressure tank diagnosis.
How to Diagnose a Leaky but not "Burst" Water Tank Bladder
It is possible for an internal-bladder type water pressure tank to behave improperly due to a small leak between the water-containing bladder and the air space inside the pressure tank. While a completely-burst tank bladder (described above) quickly or immediately converts the pressure tank to one acting like a tank with no bladder at all, a very small leak, even a pinhole leak in the tank bladder acts differently.
Photo at left, provided by reader D.S., illustrates slow water leakage out of the air valve of an internal-bladder water pressure tank that has been removed due to a pinhole leak in the water bladder. Details of this case are at FAQs .
A small or pinhole leak in the water tank bladder will send water "one way" from the tank bladder into the water tank's air space. The diagnostic clues you will see in this case include
A case history provided by a reader details the diagnosis of a pinhole tank bladder leak in the FAQs section of this article.
Water Tank Not Properly Located can Also Cause Improper Pressure Switch Operation
Iif you place the water pressure tank too far from the pump pressure switch, or at a different elevation from the pressure switch, the pressure switch control may not operate properly. Here is what Amtrol™ says about tank location:
Really most pressure tanks will work if placed almost anywhere. But if you have a problem such as pressure switch bouncing (the switch turning the pump on and off rapidly at the start or end of a pumping cycle) you can relocate the pressure switch to the new larger tank and run a longer wire to the pump or pump control relay. Other causes of pressure switch bounce and well pump short cycling are explained at SHORT CYCLING CAUSES.
Be sure to review WATER TANK BLADDER PRESSURE ADJUSTMENT if you are adjusting, tuning, or replacing the air pressure in your bladder-type well tank.
Details about how to repair or replaced a water tank bladder are at WATER TANK BLADDER REPLACEMENT.
Our sketch at left, courtesy of Well-Rite water pressure tanks [Flexcon Industries]  Illustrates how air in the upper portion of the tank compresses water in the flexible tank bladder, acting as a spring to push water into the building water supply piping system during the draw-down cycle. You'll note that at the end of the 40/60 psi draw-down cycle illustrated, the volume of water in the tank is nearly zero.
Fixing or getting rid of a waterlogged collapsed-bladder water tank: as we mentioned above, it's also possible that the torn bladder will stick to the water outlet opening, blocking water from leaving the water tank. The result will be short cycling of the water pump. We discuss water pump short cycling at WATER TANK REPAIRS. In any case the drawdown volume will be reduced and it's likely that this misused water tank will rust through soon.
Water tank bladder replacement: on some water pressure tanks, the water tank can be disassembled and the bladder replaced. You might want to ask your plumber to try this repair before replacing the entire water tank assembly.
Bladder replacement will involve draining water from the system and removing the water tank pretty much as if the whole tank were to be replaced. Suppliers such as Wessels offer replacement bladders for some models of expansion tanks and hydropneumatic tanks. In general, if you're going to hire a plumber to do this job, we recommend replacing the whole tank.
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Frequently Asked Questions (FAQs)
Question: Water tank internal bladder is stuck - how do I repair it?
I just replaced a bad water tank with a new pre-pressure tank. The pressure setting is at 29 psi according to the manufacturer. However, after hooking everything back up, it appears no water is going into the tank. I attempted to adjust the pressure switch but nothing appears to work. Could I be dealing with a back pressure switch? - Ron
Thanks for the information on the new pressure tank.
If the internal bladder has failed and collapse onto itself, can I get everything working by removing all the air pressure first and then pumping water into the tank?
There is water coming out of the water valve prior to the tank when the pump is running. However, after closing it, it appears no water is going into the tank. - Ron
Similar question: new bladder tank installed, tank won't fill with water
I just installed anew bladder tank, and it is not filling with water, is this normal? - Wess Wellmaker
Reply: Replace the Bad Air Bladder or try Pumping Up a Stuck Water Tank Internal Bladder
I'd check the pressure at your new pressure tank at the pump cut-in and cut-out points. If the pressure never changes then I'd agree that something's wrong with the hookup and no water is being pushed into the tank. If an internal bladder has failed it can collapse onto itself, stick to itself, and can prevent water from getting into the tank. But first make sure there is no closed valve that ought to be open;
A bad pressure switch would prevent water from entering the water tank if the switch is simply not turning on the pump when it should. ;
Next: when an internal bladder has collapsed and stuck to itself I think the "fix" is to replace the bladder or the entire tank and bladder assembly. No water enters the pressure tank when the bladder is stuck like that.
Since your tank is new, replacing the tank or bladder does not sound like the place to start. But even a new water pressure tank that uses an internal bladder could be having a problem filling the bladder the first time.
But according to Jeremy Rasmussen, an experienced well driller and installer, he sometimes can "un-stick" a jammed or stuck water tank internal bladder by temporarily forcing the well pump to pressurize the water tank to a pressure above the usual pump pressure control switch cut-off setting. Jeremy holds the pump relay switch closed to force the pump to keep running to increase the pressure against the stuck bladder.
Watch out: Especially if there is no pressure relief valve on the water tank there is a risk of bursting the water tank. Over pressurizing a water tank can cause it to explode, causing injury or even, as happened in New Paltz, NY, death. Watch the pressure gauge, and keep the tank pressure well below the recommended manufacturer's maximum pressure rating for the tank. If you keep the pressure below 70 psi and the tank is not already weakened by rust or damage, you should be OK.
Watch out: there are potentially fatal electric shock hazards if you touch live electrical wiring, especially in wet areas or where you may also be touching building plumbing.
Finally, check to be sure that any valves between the water pump and the pressure tank are "open" to allow water into the tank.
Wes: indeed water should enter your water tank bladder when the pump cycles on. Look for
- a closed or broken water control valve between pump outlet and water tank inlet
- a stuck water tank bladder (try briefly holding the pressure switch closed to pump up to 1o-15 psi over the usual cutoff pressure to see if you can un-stick the bladder in the tank
Watch out: do not over pressurize a water pressure tank - it can burst and kill someone
Question: bladder tank pump system worked fine until we had a burst water pipe
Hi there, we have a bladder tank pump that was working perfectly ok until Friday night when a pipe in the kitchen burst, and all the water was turned off. Now the pipe is fixed and the water back on, but the pump will only run for a few seconds and then goes off. It also isn't pumping much, if any water into the cold water tank in the loft (just a trickle running into it, mostly after the pump has switched itself off), and the other problem is, there is no water from any of the hot taps in the house.
The hot water tank is full. All valves had been turned back on. Even running the cold taps won't make the pump come on and stay on. It's currently sitting at approximate 2bar, and when it runs, it cuts out at 3bar. These figures are usual for our pump. Any clues on why its cutting out too early and why there's no water coming from the hot tank to the tanks? Any advice gratefully received! - Jack
*Sorry, that last line should say "Any clues on why its cutting out too early and why there's no water coming from the hot tank to the taps?"
Jack I wonder if the burst pipe water flow rate stirred debris in the system and clogged the pressure sensor switch. Sorry not to have replied sooner, we were deluged with questions
Question: Water pressure tank seems to be empty and water pump won't shut off
I gently rocked the tank and it does not seem there is any water in it. My pump will pump water but the water pressure will only go a little over 30 so the pump will not shut off. For now I shut it off manually and turn it on and allow it to run until we have finished taking a shower or some other task. If the bladder has failed shouldn't the water pressure still build up and then shut the pump off? - Dale
If the internal bladder in a water pressure tank has failed, the symptoms can vary a bit. Sometimes a collapsed bladder will prevent water from entering the tank, or water can enter up to the pump cut-off pressure but water won't flow back out of the tank. If that's happening the pump will turn on and off quickly as if there were a waterlogged water tank.
Question: Buried water pressure tank, now the tank seems waterlogged
Hi. Very informative site. I have a well system that was put in 6 years ago. The bladder or diaphragm tank was buried according to my installer because my double wide had no basement. He also told me the tank would be good for about 20 years.
Recently, I've experienced the symptoms of a waterlogged tank, and after discussing it with the installers front office find they warranty for 5 years (a long way from 20, but I'm certainly not calling them for any further work). 2questions: I'd like to install a new tank in an insulated box under the double wide--is this ok? I'm also wondering if I can just use the existing line coming out of the ground and temporarily not worry about digging up the old tank and rerouting the line. Thanks for any help. - Anonymous
Anon: in my OPINION, no one in their right mind would bury a conventional water pressure tank. The tank is not intended for being buried nor for soil contact, nor are its safety controls such as the pressure relief valve that should have been installed at the tank, nor are the pressure sensing controls that should be installed at or close to the tank. Such an installation cannot be serviced.
When you dig up and replace your buried water tank, if it cannot be installed inside the building in a dry heated space, it can be installed in a dry, covered, but accessible "well pit" as was common practice at well heads before the pitless adapter was invented.
Question: water pressure starts strong but quickly falls off to nothing - what might be wrong?
When we first turn on outside faucet near well house we have alot of water pressure, then it goes down to a trickle in a few minutes. Also when we have this outside faucet on, we don't have any water in the house. Our pressure tank feels empty, could the bladder be collapsed? If it is collapsed, is there a way to get it un collapsed or do we need to replace it? - Jorg
We were also wondering if the pressure switch could be causing the drop in pressure?
Jorg about the water pump pressure control switch, a bad switch will fail to turn the pump on or off at the proper time; if it were improperly adjusted it might appear to work but lead to lower water pressure.
Question: Water tank pressure creeps up higher than normal
My pump cut in pressure is 35 psi. Couple yrs ago charged tank to 33 psi. Recently my pump started short cycling. I drained the tank. Air charge read 46 psi. Lowered back to 33 psi. A few days later tank pressure was back to 46 psi. What could cause this? I changed the filter. Water flow seams normal. - Kevin
Kevin: these are great water pump and tank mysteries, no?
If you are seeing air discharge at your plumbing fixtures, see AIR DISCHARGE at FAUCETS, FIXTURES
Question: Why is there red cap over our water tank air valve?
Why is there red cap flush mounted inside of the air valve? It blocks access to the stem valve. - Lawrence
Reply: The red cap prevents accidental release of or change in the water tank's air charge
The red plastic cap on the air valve on your pressure tank is intended to prevent an amateur from messing with the tank's pre-charge of air pressure.
On many internal bladder type water pressure tanks, the water tank is provided from the factory with the manufacturer's recommended air pressure pre-charged in the tank. The manufacturer doesn't want someone accidentally letting the air out or otherwise messing with the air pressure charge if they don't know how it should be set.
Provided you follow the manufacturer's instructions about adjusting the pressure in the water tank, you can remove the red guard to access the air valve itself.
Question: how to troubleshoot air in water lines - collapsed water tank bladder as a cause?
Hi, What a helpful site. We have been experiencing intermittent air in our water lines, and yesterday had the well company come out. They repaired a couple things: pinhole found in pipe just above the submersible pump (which is 24 years old but appears to be running well). Also a weird bleeder valve arrangement that is no longer needed, and which he replaced with a brass check valve.
Put everything back down in the well and ran the water, seemed okay. However since then we notice very low water pressure, and when the water is on the pump is short-cycling. From reading your articles, I checked the water tank (well-x-trol) and am able to rock it with gentle pressure, leading me to believe there is no water in it. The pressure gauge is at 60%. My question is, is a collapsed bladder a common result of draining all the water from the system? And I guess the real question, is this repairable or do we need a whole new water tank? Thank you. - Sara
I haven't run across collapsed water pressure tank bladders due just to emptying the system of water, though I could imagine that if a tank were left empty for some time, the bladder might stick to itself. Bladders in at least some water pressure tanks are replaceable - some readers have reported success in doing so. Replacement involves shutting down and draining the system, and most likely disconnecting the tank to upend it to gain access to a removable panel through which an OEM replacement tank bladder is installed.
See AIR DISCHARGE at FAUCETS, FIXTURES for help in diagnosing and fixing the air discharge in your water piping and fixtures.
Question: water tank removal: how do I abandon a well and water pressure tank when switching to municipal water supply
I have had a water well plumbed and changed to a public water. the blue tank i was told was not in use,,though there was a leak from it. eventually it got rusted and at the end and let away the water from my public connection out. i had to turn mains off..what is going on if this belly tank only belongs to the water well, which is not in use. - Reosemary
Rosemary, if you have switched from well water to municipal supply, ALL of your old water input/supply equipment should have been taken out of your water supply system. That's because the municipality worries that contamination in a private residence's equipment could back-contaminate the public water mains.
Question: We have intermittent water pressure and the water smells - is it a bladder problem?
We are currently experience intermittent water pressure and water has slight smell. In conversing with other people thought our holding tank might have had issues w/the bladder. We haven't lost water completely and as of last night was on full pressure. Any ideas on the problem? - Karin Wilson
Reply: Diagnose the cause of intermittent water pressure first, and smell second
I'm not sure what to diagnose from your description; there could be a less-than-obvious connection between a water smell and water pressure in that in some wells, when the water level in the well drops (as it may seasonally especially in the dry season) there may also be an increase in odor in the well water as different rock fissures and different components of the aquifer feed into a typical drilled well at different depths.
Certainly we've seen that sulphur odors in well water can vary seasonally.
You could also have a problem with bacteria in the water supply or growing in the water pressure tank.
To be more diagnostic we need to understand if your "intermittent water pressure" means that at different times of the day water pressure is poor versus poor or inadequate water pressure during different portions of the pump cycle (typically just a few minutes). If it's the latter, then we might try addressing the complaint with an adjustment to the pressure switch to slightly narrow the gap between cut-in and cut-out pressures.
But if the water pressure failures are intermittent during the day, it sounds like there may be a well flow problem.
Question: why is my well and pressure tank water draw-down cycle only giving me 2 gallons of water before the pump has to turn on - short draw-down cycle troubleshooting
I have a private well with a new 7-8 GPM pump set at 300ft installed last year. I have been trying to test our 15 year old pressure tank. It is a WellxTrol WX-202 20 gallon that states it should have a draw down of 6.8 gallons. I have no pressure or flow problems and my pressure switch is set to 30/50. I ran a draw down test with my garden hose and nozzle hooked up to an outside faucet and only got 2 gallons before pump turn on (at 30psi) into a volume marked pail, but the draw down time was about 1 minute 30 seconds. Time from cut-on to cut-off (50psi) is about 15-20 seconds. There is no short cycling, at least from cut-off to cut-on and we get consistent pressure and flow.
OK, new information after an additional test this morning. I flushed a low volume toilet and the water tank pressure immediately went from cut-off (50psi) to just above the cut-in pressure of 30psi, then as the volume of toilet flow slowed the pressure slowly went down to cut-in pressure. I'll test the tank air pressure later but it looks like I need a new pressure tank. - Peter
Reply: check for a waterlogged water pressure tank, check the air volume controls, add air to the pressure tank
Peter, your description sounds as if the water tank is waterlogged - has lost its air charge. See SHORT CYCLING DIAGNOSIS TABLE for help in confirming and diagnosing both short water draw down cycle (too little water before the pump turns on) and frequent pump on-and-off cycling.
And see WATER TANK AIR, HOW TO ADD for help in getting air back into the pressure tank.
Reader follow-up: trying to get air into the water pressure tank
I drained the pressure tank from the well head so that the pressure gauge showed zero. Then tested pre-charge and found it to be less than 10psi. I added enough air to get 28psi (cut-in 30psi) then tested the performance. From zero to cut-off took much more time than before, at least double (guesstimate), and when I flushed the same toilet the pressure went to 42psi, not the 32psi I got before. So defiantly the problem was too little air pressure.
I don't know where the air went though? One thing I noticed was that as I was filling the tank with air the water pressure gauge also went up and I found I had to open the well head tap to get back to zero. This seemed to clear out and I can only assume that the bladder did not fully collapse until air pressure was added.
I re-checked the tank pressure after I had opened the well head tap and the pressure held at 28psi, so I think my bladder may be OK and not (at least completely) ruptured. I'll check the pre-charge in a couple of weeks but I think for a 15 year old tank I'll just replace it anyway. The original plumber only used the smallest marginal tank so I'll go bigger for more draw down. - Peter
Peter if you drain water out of a pressure tank down to low or "zero" pressure, that does not alone assure that you've actually gotten air to enter the tank. It could be still nearly full of water but at little or no pressure. You should be able to see at least 30 seconds of draw-down at a typical faucet before the well pump has to turn on. Or taken another way, a water pressure tank is rated for an "equivalent" draw down volume of water, typically 10 gallons or higher, if the tank is properly installed and air-charged.
Question: water tank pressure creeps up and water pump short cycling: pinhole tank bladder leak symptoms?
First off, great site with tons of information! I don't have a question so much but wanted to submit an issue I had and the resolution as it was a bit different than anything you have listed. IF you choose to use this information on your site, feel free to edit as you wish.
[At your general page on water pressure tanks found at WATER TANK: USES, TROUBLESHOOTING, I was reading about tank pressure problems and short cycling water pumps.]
We have a Amtrol Well X Trol WX-250 (44 Gallon Pressure Tank) which is about 14 years old. 40/60 Pressure Switch on our well. We noticed the well was cycling too fast. We should have a drawdown of about 11 gallons. We were getting a drawdown of 2-3 gallons.
Followed the procedure assuming I would find a waterlogged pressure tank. Cut power to pump, open valves to drain water from system. Air gauge on the tank. I should get 38 if all is tuned right maybe less if the bladder is shot. The reading however was 52 PSI. That is odd. This reading was with a dial tire gauge. Try a digital one that I have 53 PSI.
After talking with a friend who is a plumber with 40 years experience he was stumped. The only thing I could figure out is that there is a small hole in the diaphragm allowing water to leak past to equalize the air chamber with the pressure of the water (60PSI). Never have noticed air coming out of any fixtures.
So I bled off the pressure to bring it down to 38 PSI expecting to get water out of the valve in the process. No water found and tank was set to 38. Turned everything back on and things were better but I still didn't think I was getting 11 gallons of drawdown but noticeably better. Ran the system 48hrs and repeated test.
Again, cut power, drain the system and pressure test. This time I got 45PSI. How could it rise 7 PSI in 2 days?
Call the plumber but he was busy with another customer so while waiting to hear from him I call Amtrol tech support. Explain what I am seeing, what I have done as described above. The tech stated that I have a small hole in the diaphragm just like I had thought was the only plausible explanation.
I asked what options I have and he said tank replacement. He commented that this issue is one they have seen before but is one that they had a hard time figuring out for a while as the symptoms are not what is normally expected. Pressure high not low, no water from pressure valve when venting air. He stated that the tank was getting water logged but basically we caught it early in the failure process. So it had not totally failed yet.
So new tank installed and everything is back to normal. Once the old tank was removed it was quite heavy as it was getting water logged. I used a tool to remove the core of the valve to fully vent all pressure from the air chamber.
Never got any water out. Finally I tipped the tank over to see what happens and at that point I started getting water out of the tank. So it was getting water logged as the tech mentioned it was just early in the failure process.
The main reason I wanted to write you is because everywhere I looked (this site and many others) described the normal failure symptoms. Low pressure and possible water from the air valve. Another possible symptom is high pressure though. It makes sense. The air chamber should be sealed. As long as the pump is off and water drained it should be 38 or 2 lbs below cut in as your site mentioned. If it is anything different (high or more commonly low), either it was set wrong during installation or the diaphragm has a hole or is ruptured. If it is different, adjust pressure to where it should be and run it for a couple days and check again. If the pressure changes again, odds are the tank is bad.
Thank you for setting this site up and the work you do. - D.S. 8/10/2013
Thank you for the interesting water pressure tank water-logging and "high pressure" report - it helps us realize where we need to work on making our text more clear or more complete. A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. And I suspect that in the case you describe, we could have missed something to complete an explanation of the system pressure readings you observed. But with what you've said I can offer a possible explanation that fits the facts as given.
If the pressure control switch on a water pump system is working properly, the system pressure will never exceed the pump pressure control switch cut-off pressure. Your pump cut-off pressure was 60 psi using a 40/60 pressure switch. The highest pressure you recorded at the tank was 52 psi - consistent with this rule. Amtrol posed that there was a small leak in the internal water tank bladder. This makes some sense to me and leads to speculation about what' was happening in your system.
Why would water tank pressure readings creep up in just a few days?
You asked how the apparent tank pressure could "creep up" above the cut-in pressure over several days. I agree that the explanation has to lie in one of two areas: a faulty pressure control switch OR a leak in the pressure tank's internal bladder. Debris clogging can cause a pressure control switch to properly sense lower pressures, failing to turn the pump on consistently, but debris clogging at the switch does not normally cause tank over-pressure. This does not sound like the situation you describe.
Other internal bladder type water pressure tank odd behavior can be caused when a bladder sticks to itself - often causing very small draw-down volumes as water cannot enter the tank. This too does not sound like the situation you describe.
An explanation for the unexpected increase in water pressure in the tank combined with shortening draw down cycle may be that water under pressure leaks out of the bladder into the space between tank and bladder through a small leak or opening. Because the hole in the bladder is so small, it is quite possible to turn on water in the building and receive water at a lower pressure and quantity than normally delivered from the pressure tank because the rate at which water under higher pressure could leak back into the bladder interior would be very slow. In addition, water accumulating in the air space outside the bladder reduces the volume of that air space, thus reducing the draw-down water quantity and leading to short cycling.
Effects of a pinhole or small bladder leak in a water pressure tank
Re-stating what I think is going on, at the upper end of water tank pressure range that occurs during each pump-on cycle, some water is forced out of the water-containing bladder into the space between the steel tank and the bladder where it accumulates. The ability of water to return to the bladder interior may be less than its ability to leak out of the bladder due to the position of the particular pinhole or small leak. That is, leakage tends to be unidirectional, pushing out of the bladder into the air space only at the top of the pressure cycle.
The result of water accumulating out of the bladder and in the space normally occupied by air in the pressure tank is that the volume of air-space is gradually reduced, leading to short water pump on-cycles just as occurs in a bladderless water pressure tank that has become water-logged.
Why no water came out of the air valve at the pressure tank top
Why, then might you have not been able to get water out of the leaky pressure tank through the air valve (as occurs in a water-logged bladderless tank)? Water has to be trapped within the tank's air space; the air valve is at the top of the tank. Water in an upright tank will be at the tank bottom.
Opening the air valve, even releasing all of the air pressure remaining in the tank will still leave water in the tank air space at the tank bottom. Upending the water tank might seem a course that would allow water to drain out of the air valve, but keep in mind that if there is no other way for air to enter the tank during this process, it will be difficult to drain any water out.
Here is a similar example; if we want to drain water out of a water heater tank, the tank drain, located at the bottom of the tank is opened. But unless we open a valve at the top of the water heater tank (often we use the relief valve for this purpose), because there is no path for air to enter the tank except through the same valve that is draining water out, the rate at which water leaves the water heater tank is very very slow.
Water drains out at a dribble until enough vacuum is created inside the tank to stop water leaving and instead draw a gulp of air into the tank. Then more water dribbles out. This is a very very slow process occurring through the 1/2" diameter tank drain valve opening. Now translate this situation back to an "upside down" water pressure tank trying to drain water out (and let air in) through the 3/16" diameter air valve opening. Little or no air can enter and little water will thus drain in out except at a very slow rate.
[It is also worth noting a condition that probably was not occurring on your system: in some situations we are measuring or sensing tank pressures differently at the pump control than at a tire gauge used at the air valve. The air valve location senses air-pressure in the air space around the bladder, while the pressure gauge senses water pressure in the piping system - under normal circumstances that includes water pressure inside the bladder. In a normally-operating system these pressures (air and water) should be the same; but if a bladder is damaged and sticking over the water outlet, that pressure consistency might be lost.]
Based on the water pressure gauge I feel that my 40/60 pressure switch was operating properly. When replacing the pressure tank I also replaced the pressure switch, connecting pipe for it and pressure gauge. These items are pretty in expensive to they were done as preventative maintenance as I don't want to go back and address these other items in a few months or so. The pressure gauge was showing signs of sticking as it was dropping once it got to about 50 PSI. Of course the pressure gauge had nothing to do with the operation of the pressure switch other than provide feed back as to what pressure the water is at in the system.
One symptom that may be worth mentioning is that when I shut off the power to the well and opened a drain valve next to the pressure switch to drain the system I also opened a faucet in the laundry room 10' away from the pressure tank as well as a bathroom faucet upstairs. This was done to try and drain the water from the house pipes the one upstairs opened to allow air in to speed things up. Like you mentioned in draining a water heater. So what I saw that may be worth noting.
While that valve was open, I did still see a trickle of water coming out of the valve at the pressure switch. I attributed it to water draining back from the house. However in my case it may have been water leaking from the small hole in the waterlogged pressure tank. When I disconnected the tank it was quite heavy (compared to the new one) and it continued to drain water very slowly from the tank even though the core of the air valve was removed. Also when I tipped it over it did drain water from the air valve. This is shown in the photo that is attached. Of course one would have to be certain that any trickle from that valve is not coming from the house plumbing as it is draining to the low point in the system.
I suspect that I didn't get any water from the air valve when venting air from 52 back down to the proper level of 38 because as you mentioned the air valve is at the top of the tank and it appears that no air never left the tank (via plumbing) other than what I vented explaining the high pressure. Because of this head space the water never reached the air valve when venting while it was hooked up. Once I could tip it on its side then I could get water to exit from the air valve. - D.S. 08/11/2013
I think you've got it just right. As long as water in the pressure tank bladder was pressurized and unable to exit at a tank drain, when the water tank is removed and placed upside down or on its side with the air valve facing down, pressureized water in the bladder might indeed slowly leak back out of the (stretched) bladder, into the air space of the tank and out of the air space slowly through the schrader valve.
And I agree it's much cheaper to replace old plumbing parts during a water tank replacement than to have to re-visit the the topic later.
Thanks for the photo of your water tank. - DF
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