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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
Water tanks: this article describes the purpose of water storage and water pressure tanks, how water tanks work, what goes wrong with the water tank (such as water tank leaks, loss of air charge, corrosion, failure to admit water) and how to fix water tank troubles. We explain the different types of water tanks such as tanks using an internal bladder or diaphragm, bladderless steel, fiberglass, or plastic water tanks, and water tank pressure and air controls and valves.
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Our complete list of water tank installation, diagnosis, & repair articles is at the end of this page.
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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.
What's the Difference Between a Bladder Type Captive Air Water Tank and a Conventional Steel Bladderless Water Tank
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.
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! Bladder type or captive-air water pressure tanks and their repairs are described just above and in more detail at WATER TANK TYPES.
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.
Why Air is Needed in a Water Tank
Air in the water tank acts like a spring or cushion which serves to smooth the delivery of water into the building as the pump cycles on and off. That's why we call this the water pressure tank rather than a water storage tank - though for most people these are the same device. Sketch courtesy of Carson Dunlop Associates.
This air cushion effect prevents the water from surging (much) at the plumbing fixture as the pump turns on and off as water is running during use of the fixture (such as a sink or shower).
More important, this cushion effect prevents short-cycling of the pump on and off, which in turn prevents pump burnout or water pressure control switch damage which could occur if the system switches on and off too rapidly.
Why is a pressure tank with a buffer or spring or cushion of air needed? Water itself is not very compressible.
Since a pump can usually pump faster than the flow of water out of a single faucet, as soon as the pump switched on, water pressure would build way up and the pump would immediately switch off. Water would not flow nicely from the tap. Instead it would come in a series of squirts. Worse, you'd burn up the water pump or pump control switch by this rapid cycling.
The air cushion in the tank acts like a big spring which is compressed by water pushed into the tank by the pump at the same time that water is also flowing out of the pump, tank, and piping system into the building to whatever faucet has been opened.
So while water is running in a building served by a private well, part of the time the water flow is being maintained only by air pressure in the water tank, and part of the time the water flow is being boosted by the pump during its on cycle. And during the pump's on cycle, it is both pushing water into the house and re-pressurizing (by compressing) air in the water tank.
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Frequently Asked Questions (FAQs) about water storage tanks and tank controls
Question: Why do I need a water tank on my well pump? Can I run the water pump without a water tank attached?
Does a home water pump need a water tank. can i run the water pump without a water tank. some days no water will reach 2nd floor. and some days even on the 1st floor water is weak. currently running no pump. - Ian 09/2011
Answer: Generally yes you need a water tank for proper well pump operation, but there are a couple of exceptions
Why do we need a water pressure tank?
Question: Rooftop water tank leaks into elevator shaft?
We just had an issue with the water tank on the roof whereby an obstruction in the main water feed line out of the tank that prevented water from flowing out of the tank and in the building. Supposedly the overflow valve in the water tank failed causing an amount of water to overflow from the tank. onto the roof area and down into the elevator which caused water damage on the top of the elevator cabs ...there is now only one elevator in the building and the other one has to be run manually. The risers were drained in he basement to remove the sediment from the lines, The water was rusty for quite some time as well as off completely.
Can you offer me your expertise on this alleged unforeseen emergency The building is almost 50 yrs old Was built in 1966. thanks
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem whether it's with the failed valve in your water storage tank or in explaining how water moved from there into the elevator shafts. That said, it sounds as if you are describing a triple fault:
How is it the case that water from a spillage on the rooftop got into the elevator shaft and why wouldn't rainfall or snow-melt have done the same? I'm not sure what other research or support you are requesting, but if you have a specific question let me know and I'll do my best.
Question: Installing a pressurized system & Flushometer Valve Toilets & Urinals on a Well & Pump Water Supply System
I have space above the rest rooms and would like to install a stand alone pressurized system that is fed by the existing residential system, but would provide the gpm and pressure to function the commercial units. Likely to be a total of 3 toilets and two urinals.
Any ideas or plans available? Thanks, Bill
Reply: Be sure that your well water supply system, pressure tank, pressure, and water supply piping diameter & flow rate can support flushometer valves; consider waterless urinal fixtures.
Bill, we provide a detailed answer to this question at FLUSHOMETER VALVES for TOILETS URINALS
That's why the standard water supply pipe diameter to the fixture is 1 1/4" rather than the common 1/2" or 3/4" water supply piping found in residential and light commercial buildings using conventional tank-type toilets.
Question: Does the type of water storage & pressure tank affect water odors?
Do the Bladderless Steel Water Pressure Tanks help reduse the smelly water problem? - Joe Y
Joe y: I'm not sure how the type of water pressure tank would reduce a smelly water problem. In most communities you can have your water tested for free by water treatment companies and sometimes by other agencies.
You need to identify the source of odor and based on that information an expert can recommend a water treatment system that can reduce or remove the unwanted odors. See ODORS in WATER for details on diagnosing and fixing water smells or odors.
Question: Weep holes in well piping prevent conversion from bladderless to a bladder type water pressure tank?
My well guy told me that there are "weep holes" in the well pipe that is deep in the ground. It's expensive to pull a well pump and seal those weep holes so I really have to stay with a bladderless system. The home improvement places do not carry bladderless tanks anymore but they are still available. - Anonymous
Reply: Your well guy may have been referring to a snifter valve that needs removal if changing to an internal bladder water tank
Anonymous: frankly I'm unclear why the system you describe would make one iota of difference between choosing a bladder-type or bladderless water pressure tank. In either case the tanks have the same working effect on the plumbing system.
Leaky well piping should be replaced
If your well piping is leaking and you are losing tank pressure back into the well after the pump shuts off, the proper repair is to replace the leaky well line (saving burn out of the pump), though you could try installing a check valve above ground on the line that returns to the well. Review this with an experienced plumber so you get it right.
Snifter valves for air volume control need to be discontinued if changing to an internal bladder water pressure tank
However, it is certianly true that on some submersible pump installations that used a bladderless water pressure tank, a snifter valve system was used to maintain the air volume in the water pressure tank. The snifter valve system can include an air inlet valve above ground near the water pressure tank and an air inlet and water drain outlet port that is installed on a special fitting on the water riser pipe inside the well. Where a snifter valve system is installed it needs to be removed when changing to an internal bladder water pressure tank.
We discuss snifter valves on wells and water pressure tanks in detail at WATER TANK AIR VOLUME CONTROLS.
Question: How is the air volume controlled on older bladderless water pressure tanks & how is it adjusted?
I have a 120 gal galvanized water tank that's beginning to corrode. This deep well services my house and lawn sprinklers and it's worked fine for decades. I read about the AVC which I have and it was replaced recently.
I was wondering how it is adjusted with the adjustment screw? It gets "stuck" sometimes and I have to mess with the screw to stop air bubbling into the house. However, then I get water coming out of the screw adjustment which I had left slightly cracked open because I didn't realize there was a float inside the unit. I was also wondering if I could switch to a bladder type tank or if it is better to stay with what I have. I've read a lot here and thank you for the useful information.
So are there any advantages to going to a bladder tank? One thing I am not sure of is how air is pumped into the tank I have. Obviously, I would have to stop the air addition if I go to a bladder system. My system doesn't have one of those disk shaped thingamajiggers that I read about in here that adds air. Any help would be appreciated. - Steve J.
I made an error in the statement below, the galvanized take is 82 gallons in volume, not 120.
After more research, sounds like the non bladder system I have is best because the addition of air and occasional automatic air purging removes some well water gasses resulting in a fresher water supply. People kept referring to the non bladder system as "old" technology but it appears to also be better technology.
I have a U.S. Gauge Type 310WJ installed but that appears to just let air out of the system, not add it. Am I missing something about how that gauge works? The description written in here says that it adds air with each pump cycle but looking at the gauge, I don't see how that's scientifically possible.
I would still like to know how the air is pumped into my system. Perhaps I need to contact US Gauge. Thanks again for all the details written here - it was a big help.
Reply: Reference to article describing methods of air volume control in water pressure tanks
Systems that automatically add air typically do so by allowing a valve to open to let air into the system when the in-tank pressure drops, closing again as in-tank pressure rises. Indeed it's scientifically possible; some such devices tend to clog or fail over time however.
The types of air volume controls used on bladderless water pressure tanks are explained beginning at WATER TANK AIR VOLUME CONTROLS. You'll also want to review snifter valve systems used for air volume controls as we explain in detail in that article.
Question: Since installing a bladder-type water pressure tank we keep losing water pressure
A few years back I had our old water tank replaced with a HT20 bladder tank, every since then we loose water pressure as the water runs (taking a long shower, watering the garden ( we cant run a sprinkler in the garden as it looses the pressure to keep it flowing)) I have been told it could be many things, I adjusted the pressure in the tank from 20 to about 28-30 and we ran out of water pressure faster, so I adjusted it back to 20 and the water pressure last longer, now I was told that maybe I need a bigger tank. I was told that I should have about a 30-35 gallon instead of the 20gal. Should I invest a couple hundred in a new tank or could it be something else? - Phil
Reply: check for a dirty or clogged water pressure control switch
Changing the water pressure tank size, from smaller to a larger unit, does not change water pressure delivered in the home. Pressure is determined by the capability of the water pump and the settings of the water pressure control switch.
If you are not running out of water but water pressure falls off too much during the pump cycle, the gap between pump cut in and cut-out may be too large. You can change this by adjusting the pump pressure control switch. Details are at WATER PUMP PRESSURE CONTROL ADJUSTMENT.
But we have heard from quite a few readers who complained of water pressure variation problems after changing out their water pressure tank. Often the problem is traced not to the new tank but to debris and crud stirred up in the water piping system during the plumbing operation. If the water supply is contaminated with silt, mud, debris, or if water piping includes rusty iron, debris can easily clog the water pressure control switch sensor opening on the bottom of the switch, or it may clog the small diameter pipe nipple used to mount the pressure control switch to the water system.
Replacing the clogged pipe nipple and pressure control switch can fix that problem. But if the water supply has silt or mud in it you'll also need to install a water filtration system or the clog problem is likley to recur again soon.
WATER PUMP PROBLEM DIAGNOSTIC TABLE lists other causes of water pressure and flow problems along with recommended steps to confirm the diagnosis and cure the problem.
Follow-Up: Adjusting the pressure control switch didn't work; I replaced the switch. But water flow still falls off during use.
I tried what you recommended and adjusted the gap on the pressure control switch and didn’t effect anything at all, so per the recommendation from my local hardware store I replaced my gauge and the pressure control switch to a 30/50 one. I have more pressure at the beginning but the water flow diminishes after running it for awhile (it is better though and the pressure is better as well). Do you think I need a bigger tank or could it be something more serious like a well problem or well tip? If it could be the tank size could I add a 20-30 gallon tank (in line) before the other 20 gallon tank so I would have more water storage or doesn't it work that way?
Reply: Normal water pressure variation during the well pump operating cycle
Phill, it is normal for water pressure in the building to vary through the pump cycle, from the low (cut in) to the high (cut out). A larger water pressure tank won't change those pressure limits but it would give you a longer draw-down time between pump on cycles and in that sense water pressure would drop more slowly.
Question: Water tank pressure drops after I shut off water into the building. What's going on?
My tank pressure is dropping although i have shut off the main valve from the pressure tank to the house and have a check valve from the well to the pump to prevent pressure drop. Still the pressure gauge is still slowly loosing pressure. Has anyone experienced this? help advise please. thanks. - Rey.
Reply: Check for a leak in the well piping, foot valve, or pressure tank
Rey: if the water pressure tank pressure falls after you have closed valves into the building, one of these may be the problem:
Question: Water flow stops completely, pump comes on, water does not flow, delays in return of water pressure
Having a problem where water stops flowing completely out of the faucet at about 40 PSI, then the pump kicks in at about 35 PSI. There's a several second time frame where no water comes out (very inconvenient in the shower) while waiting for the pump to cut in.
I can remove this delay by turning the cut-in nut on my pressure switch (9013FSG 2) clock-wise, but the point at which there's no water output drop-off before the pump starting results in about a 65 PSI cut-off point.
I can't see this high a pressure being good for my pump or the water fittings throughout the house. Does anyone have any ideas about how to get the pump to turn on while water is still flowing? I don't really understand the water tank, so I'm wondering if I need more pressure in it to keep the water flowing until the pump cuts in. Help! - Greg F
Reply: Check for debris clogging of the pressure control switch
Greg I wonder if your pressure gauge is clogged with debris and not giving an accurate picture of system pressures, or if the pressure control switch is itself debris clogged. Certainly your description sounds like a sticky pressure control switch.
Question: Are well water tanks recyclable?
Reply: Yes well water tanks are often recycled
Well water tanks are often collected and recycled, especially by larger plumbing and well drilling companies. To recycle an internal-bladder well water pressure tank the tank is cut open and the bladder is removed.
The remaining steel is delivered to a recycler. This is a useful detail to know about not just because we recommend recycling whenever possible.
Our photo (left) of a bladderless steel water pressure tank illustrates a unit that was replaced by a newer internal bladder tank. The steel tank will be taken away by the installer (avoiding leaving something difficult for the homeowner to dispose-of), and stored in the installer's junkyard until that company has accumlated enough tanks to have them hauled en-masse to the recycler.
The plumbing company that opens water pressure tanks has an inside view of problems that may have developed with the bladder or with the tank itself - useful water tank failure cause and effect data.
Question: Water tank problems return after draining & air-charging
Twice now we have experienced air in our water fixtures. I have drained the pressure tank and everything has worked fine for approximately 2 weeks, and then the problem has started again. Any advise as to what could be causing this. Our pressure tank is probably about 30 years old and it is a private well. - Mike 1/7/12
Mike at AIR DISCHARGE at FAUCETS, FIXTURES (article link in Related Topics section near page top) we give diagnostic procedures for air in water fixtures.
Question: How do I set the pressure in a water pressure tank?
I have a single outdoor water line that i'm using for an outdoor shower... i've put a pressurized bladder 85gallon tank for naturally hot water (sun blasts this thing in summer) and water storage... to store a reasonable amount of water, what would you recommend i set the psi on the bladder to? do i set that when empty or when there is water... i think incoming pressure is about 30psi - Dave 1/20/12
Dave, please see the instructions at WATER TANK BLADDER PRESSURE ADJUSTMENT
Question: our water pressure was low - not over 30 psi
I found that after being in the home for a year, that my water pressure was low. I replaced the pressure switch and the pressure gauge. Watching the gauge it shows that the pressure goes to approx 30psi and no higher. The contacts on the pressure switch show closed. If I turn the power switch off, the pressure guage goes to zero. Do I have a pressure tank issue, foot valve issue or some other issue? - Bill B
Bill, you may have a well with very modest flow rate, or a pump that is damaged and can't reach cutoff pressure, or a leak in the well piping that has the same effect. When water pressure drops to zero on the gauge, if it really is zero no water would be coming out of your water faucets. If this is the case then the pressure control switch is not turning on the pump when it should, OR the pump is not working OR the well is out of water.
Question: can a water pressure tank or storage tank be installed underneath a mobile home?
Can a water reservoir tank be placed under a mobile home or does it have to be next to the well pump? - Jay 9/13/2012
Question: why do I see 600 gallons of water stored in my basement?
Why would there be two 300 gal plastic water storage tanks in my basement other then storage? Could it be a fix to something problematic? - JD 9/30/12
When we see very large on-site water storage at a private house we figure that the ability of the well to deliver water, its flow rate or recovery rate, is very very minimal - someone installed large water tanks intending that the pump and well fill those tanks very slowly, over time, including when no one is using any water (at night when you're asleep for example) so that when you need water there is some stored in the tanks.
What this means to you is that your well is not very effective and you may need to address that problem soon.
Question: we have water at our well but not in our house
have water at well not in house - Anon 10/6/12
See WATER PRESSURE PROBLEM DIAGNOSIS TABLE (article link in Related Topics section near page top) for a tabular guide to diagnosing your lost water pressure problem.
Question: our water tank doesn't seem to hold enough water
the tank fills with soemthing like 3 gallons - i think that's not normal, how do I fix it? - Anon 10/17/12
Anon, take a look at the labels on the pressure tank, or the instruction and installation guide to see what the rated tank capacity is in gallons of water; if you don't have that information tell us the brand and tank model (send along photos if you like) and we'll look it up for you. If the tank is one that uses an internal bladder and you cannot get water to enter the tank the bladder may have collapsed and stuck to itself. If the tank is not a model that permits internal bladder replacement, the tank is shot - needs replacement.
If your tank does not use an internal bladder then the problem is elsewhere, with the well, valves, piping, controls - I'd need to know more.
Question: our pre-charged water pressure tank does not include an air control valve - do we need one?
we just purchased a pre-charged pressure tank. it didn't come with a air control valve kit. do we need to purhcase the kit? the pump is working without it - Cheryl 10/17/12
Question: after I accidentally cut off power to our well pump we lost all water pressure - what's wrong?
I was fixing some issues with the insulation in my pump house and the power to the pump was cut off inadvertently. The whole system lost pressure and the pressure tank emptied completely. Am I supposed to bleed the system to get back to normal pressures? - Tim 12/15/12
Tim, it sounds as if you might have a bad check valve or foot valve that let the system drain back onto the well.
Question: how do I control filling of a water storage tank and booster pump system in Venezuela?
I will like to have information if this product is available. I bought a condo in Venezuela. There we have a cold water tank inside. When we take water from home, the motor start and when we close the tap, the motor stop
now all tanks from all condominiums are filled each day at around 6:30pm by a giant tank (probably underground).
The problem is we have to switch off the motor (have to be there at this time or switch the valve if we plan to not be there) and turn an valve, then water flow in the water tank until the float (bulbe and not electronics) stop the water.
It is the general and basic system used in South America and I heard in few other countries too, as you can see very primitive.
Now I will like to know if someone or a company have the brightest idea to build a electronic system to make it all completely automatic
I means, timer, open-close valve and switch on/off the motor.
Because of course the motor switch have to be on once the tank is full, the motor not turn but in standby until someone take water from home, and stay open until no one need anymore water, then the motor power off, (not the switch)
Can you tell me something about it. This is a blue plastic tak about 7' long, plastic. - anonymous 12/27/2012
We'd like to help but I think I may need a few added details. To start, we have a very similar system here at our location in Mexico. A tanque atop the building is filled at various times by means of water pressure from a city system. The tank fill-up procedure is stopped by a mechanical valve much like a toilet float. I think that's what you have as well. With that system the water storage tank will fill automatically with no trouble - we leave the manual fill-valve from the city open at all times; It will feed water into the top of the water tank until the tank is filled, then the valve at that location stops the fill process.
If you need to manually open and close your tank fill-supply valve manually it may be because your fill pipe enters your tank bottom - in that arrangement, if you didn't close the fill valve water would drain backwards out of your water tank back into the supply system - a bad design for several reasons including the risk of back-contamination of the main supply by a contaminant found in an individual home's water tank.
The pump system you describe is a common installation here in Mexico as well, though not on most homes - most buildings supply water into the building by gravity - elevating the water tank if needed to improve water flow rate and pressure. But for homes in which occupants want or need more water pressure, a booster pump is installed.
If a water pressure booster pump is installed by itself, the pump indeed turns on as soon as you start running water and turns off when you stop running water. This is a bit hard on the pump and shortens its life. A better installation is to include a water pressure tank in the plumbing system - usually next to your water supply tank and water pump; the pressure tank allows the pump to turn on and off under control of a water pressure switch (typically on at 20 psi and off at 40 psi);
With that design and paying attention to how water is delivered (to the top of your water tank and controlled by a mechanical valve) you should not need a more costly electronic sensor and valve control system.
Send me some photos and sketches of your water supply system and we can perhaps comment further and more accurately.
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