Schematic of a bladder type captive air water pressure tank (C) Carson Dunlop AssociatesBladder Type Water Storage & Pressure Tanks: Diagnosis & Repair
     

  • WATER TANK BLADDERS & CAPTIVE AIR - CONTENTS: How to diagnose and repair water system problems when an internal bladder water tank is installed. What is the difference between a bladder type water tank and a glass lined no-bladder water tank? Broken, burst, busted or leaky water tank bladder diagnosis & repair procedures
  • POST a QUESTION or READ FAQs about diagnosing and repairing problems with water tanks that use an internal bladder
  • REFERENCES

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Internal bladder type water pressure 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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How Bladder-type Water Pressure Tanks Work - Pressure Tank Diagnosis

Photograph of a sketch of a water pressure tank in cross sectionPrivate well and pump systems include a well (the water source), piping from the well to the building, a water pump, and a water tank to which building water supply plumbing is connected.

[Click to enlarge any image]

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.

Schematic of a bladder type captive air water pressure tank (C) Carson Dunlop AssociatesAs 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 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 water tank (C) Daniel FriedmanBladder 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

Steel water tank (C) Daniel Friedman

Bladderless Steel Water Pressure Tanks (photo at left and sketch just below) use a single steel tank interior to hold both the air charge and the water supply.

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.

What Goes Wrong with an Internal-Bladder type Water Tank? Common Water Tank Failures

Bladder type Well X Trol Water Tank (C) Daniel FriedmanWater 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 bladder prevents 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 (or might) increase above standard air charge pressure as water accumulates in the air space, also leading to pump short cycling and an apparent water-logged pressure tank even though only air comes out of the tank top air valve. Details are below at PINHOLE LEAKS in WATER TANK BLADDER

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

Water tank air valve test (C) Daniel Friedman S PriorIf 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.

  • If water comes squirting out of the tank top air valve, the captive-air bladder type water tank has burst or become torn or leaky, and repair is needed.

    Thanks to reader Steven Prior for the photo (above left) showing water coming out of the air charge valve on a water tank. Most (not all) water pressure tank models using a bladder isolate water inside the bladder - meaning that water coming out of the air valve shows a burst bladder.

    Note: Usually in a bladder-type water pressure tank the water is in the bladder and the air is in the tank outside the bladder. There are a few bladder-type water tank models in which this design is reversed - water is in the tank and air is in the bladder - more likely with fiberglass tanks.
  • A second symptom of burst water tank bladder: if air is found squirting out of plumbing fixtures it's possible that the cause is a burst bladder in the water tank; the tank's air charge is being forced out into the building plumbing system. This symptom won't normally continue once any excess air in the pressure tank has been lost - but the problem may remain, showing up as pump short cycling.
  • A third symptom of burst water tank bladder: if the water tank is full or nearly so and you are unable to drain water out of the tank, a burst bladder may be blocking the tank at its bottom. A burst water tank bladder can collapse at the water tank bottom, preventing water from leaving the tank. The result is no water pressure in the building and perhaps an inability to drain water from the water tank itself.

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

Water pressure tank bladder leak test (C) InspectApedia

Pinhole Leaks in Water Tank Bladder: abnormally high air pressure, short cycling well pumps

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

  • Shorter water pressure tank draw-down cycle than normal, with smaller quantity of water delivered before the pump turns on - water pump short cycling
  • Water tank pressure measured at the air gauge or schrader valve on the tank top will creep up to above normal levels. Bleeding air out from the tank top will prove a short remedy and pressure will creep up again. The rate of pressure increase measured at the tank's air valve will depend on the size of the leak out of the bladder and the quantity of water used in the building, thus the number of pump on-off cycles per day.
  • Unlike the "burst bladder" case described above, in the case of a pin holed bladder leak, air can be released from the water tank's top mounted air valve, but no water will exit at this point if the tank remains upright - at least not until the tank is 100% saturated.
  • With the pump turned off and water pressure drained from the system, the water pressure tank will be abnormally "heavy" due to the presence of water in the air space in the tank.

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:

The Well-X-Trol should be installed as close as possible to the pressure switch. This will reduce the adverse effects of added friction loss and pressure switch bouncing, and the difference in elevation between WELL-X-TROL and switch.

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 WATER PUMP SHORT CYCLING CAUSES.

How do We Replace or Repair a Water Tank with a Burst Internal Bladder?

Well Rite Water Tank Bladder Stages

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] [2] 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.

Problems with an outdoor faucet installed between well and pressure tank

Reader Question: 5/26/2014 Gary said:

I have an odd situation, my neighbor's set-up is... she just had a new well and pump put in 5 years ago. She called me the other day fearful that her well was dry. (the problem with her first well!) I checked the system and the problem was, as she turned on an OUTSIDE faucet, one that is between the pump and the house, the water would run for 5 minutes then stop.

After 2 or 3 minutes the pump would come on ands pressure would build back up. I replaced pressure switch and pressure gauge and inside the house the system works great! Ran all faucets inside, pressure dropped to 40PSI, switched turned on the pump, back up to 60PSI and shut off.

This ran for several cycles with no problem. Then we turned on the OUTSIDE faucet again, same thing happen. Ran FULL BORE for 5 minutes, pressure dropped to 40 then ZERO and nothing for 2 or 3 minutes until it kicks back on. I feel like the pump is shutting itself off to prevent overheating but not sure why the pump is not kicking on at 40PSI. Any help is greatly appreciated! Thanks Gary

Reply:

Gary,

Nice going on the debug work done so far.

If you can take a look at the water for sediment or debris level and find that it's high, it's possible that even the new pressure switch is being debris-clogged.

Reader follow-up:

Thanks Dan. We live in a high sediment/iron area (Triad of NC). She has a whole house filter plus a backwashing iron filtration system. She just had (three months ago) the iron system cleaned/regenerated. Of course is all 'post' the pressure tank.

However, when I replaced pressure gauge and switch, I opened the shut off valve from the house ever so slightly to allow water to drain back toward the tank it flowed well through both stems off the line. Also, after turning on the outside faucet and the switch NOT cutting on as it should we retested the system from the inside, flushed toilets and opened faucets and it worked like a charm.

I feel it has something to do with that outside faucet. It is not attached to the house, as it is a frost proof faucet 50 feet from the well near a plant bed which is 50 feet from the house. Is it possible that the outside faucet is creating a pressure issue? Thanks again.

Reply:

Undaunted by the warning not to speak beyond one's competence I note this as a working note not an answer: the water pressure control switch companies tell us to install the switch as close to the pressure tank as possible. Readers have wondered what difference it makes - thinking that water, not very compressible, should transmit system pressure uniformly through the system regardless. I haven't yet found the reason for the "close to" advice but your report might be a clue.

What if, for example, a check valve on the house side is preventing the water pressure drop in the outside faucet line from being transmitted to the control.

I need a schematic: what are the relative locations of

Well component schematic (C) InspectAPedia.com Gary CornsWell, piping to building, pump, pressure tank, pressure control switch, outside faucet.

Reader follow-up:

5/29/2014 Gary said

Let me work on that schematic. I am by no means a plumber so I ask this question from a "ignorance is bliss" perspective.

[Click to enlarge any image]

But, is it possible for the faucet to exist and work BEFORE the pressure tank? As I understand the workings of a well system, I thought the water ran from the well to the pressure tank with aid of the pump and that the pressure in the tank 'pushed' the water though out the house. If the faucet is off the 'main line' from the well to the house, how would that even work?

Reply & Reader Comments:

Well it's nice and neat but I've become still more brain damaged trying to figure this out.

Let's see if we can just write down the sequence of connections or figure out the piping by some tests.

Tell me what's incorrect in the following:

1. Your actual pump is in the well - a deep well pump, either a submersible or a 2 line jet pump (as I don't see "pump" in the aboveground components list)

Correct. A deep well pump. (maybe 200+ feet, with excellent flow)

2. The pressure tank and switch that control the pump are remote from the well, presumably indoors

Correct. Yes the tank and switch are in the basement approximately 100 feet from the well

3. The pressure tank supplies water to the building through a water filter and iron filter

Correct. The water enters the house through the wall of the basement right at the tank/stitch.

4. We are not sure how water is delivered to the remote outside faucet

Correct. It is between the pump and tank in the lawn.

4.1. look indoors for a shutoff between pressure tank and outdoor piping that you can confirm (by closing it) shuts off the outdoor faucet

There is a shut off valve right at the tank for controlling flow to the house. If I shut that off and water still comes from the faucet it must bypass the tank. I will try that over the weekend.

4.2 If there is none then possibly in an odd piping arrangement the outdoor faucet is floated on the line between pressure tank and well

This is possible. I can determine by shutting off the in-flow valve to the house. I will try that over the weekend.

If 4.2 is correct then if there is a check valve near the pressure tank, that would make the pressurized water flow just "one way" from well into tank and on to building. If this were the case then if the pump is not running (pressure switch says it's at cutoff pressure or pressure has not fallen to cut-in pressure) you will see only a brief burst of water at the faucet (from what's in the piping) before flow will drop to zero.

But flow should continue again if enough water is run in the house to cause the pump to turn on.

If this is the case it's a troubling set-up.

Reader follow-up:

I believe there is a check valve right as the well pipe comes into the house just before the tank. It looks kind of like the attached image, except longer and more rectangular in shape. This sounds like the possible culprit. If the faucet ‘floats’ between well and tank and there is a check valve preventing back flow, where does the pressure come to force the water from the outside faucet? Could the check valve need replacing?

Reply:

all of item 4 makes me suspect the faucet is on the well line between well and house. That would have worked in the past if there were no check valve in the house, just in the well (which is a common design).

But if someone replaced parts, added a check valve in the house (say because the foot valve in the well was losing prime) that would or could result in the snafu you describe currently.

If you get no water at the faucet and then do get water when use of water in the house causes the pump to turn on, that'd be confirming.

Reader follow-up:

I’ll do that check over the weekend. If it looks like the faucet is floated between the well and pump, should the check valve be removed? Just wondering what the fix might be.

Reply:

Removing the check valve at the pump will probably let the faucet work again, but if the check valve was added to counteract a failed footvalve in the well you'll find that the system loses prime.

Still, going back to your initial remarks, you have water running "full bore" for several minutes, then pressure drops down, then pressure stops entirely, then after a "rest" the pump and pressure appear to recover. To me this sounds like a debris-clogged pressure control switch, with the effects showing up more severely at an outdoor faucet floated on the line between well and pressure tank. That's because the volume of water in the well piping would not be likely to be enough to give 4-5 minutes of water at the outdoor faucet.

 

 

Continue reading at WATER TANK BLADDER PRESSURE ADJUSTMENT or select a topic from the More Reading links shown below.

Or see WATER TANK BLADDER REPLACEMENT

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WATER TANK BLADDERS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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