This article describes how to diagnose the loss of and need for air in a water tank, how to add air to a building water pressure tank, and how to detect and correct air and water leaks in a building water supply system where a private well is the water source.

We also discuss how to adjust the building water pressure by setting the cut-in and cut-out pressure on the pump pressure control switch.

What are the signs of loss of air in the water tank

Several alternative procedures for adding air to a water pressure tank are described below along with advice about what to do when things go wrong, such as finding air and water leaks.

Readers of this document should 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 left is used with permission of Carson DunlopAssociates, Inc. in Toronto. [Click to enlarge any image]

• Short Cycling of the Water Pump:
  
  If you hear the pump cycling on and off every few seconds when water is running in the building, or if you see the water pressure squirting in short bursts at the water tap, the pressure tank needs air.
  
  Also see more causes of water pump cycling
  
  at WATER PUMP INTERMITTENT CYCLING where we note that something as simple as a running toilet could be the cause of this trouble.


• Condensate marks or line on the water tank:
  
  If on the outside of a water pressure tank the line of condensation is in upper 70% of tank (or higher than the normal condensate stains if such marks are visible on the tank) then there is not a large remaining air reserve. The water pressure tank probably needs or will soon need air.
  
  Technical notes: This article explains two basic cases of water pressure tank problems that can result in water pump short cycling:
  
  1. Too little air in the water pressure tank:
  
  Unless you live in a climate where there is never condensation on the exterior of the water tank, normally the (lower) portion of the tank that contains water will be cooler than the upper tank, causing the condensation of water onto the tank surface.
  
  If the condensate line is high on the water tank this means it's filling up with water and there is not enough air charge. (Air resides at the top of the pressure tank and water in the tank bottom.) (Water Tanks in Dry Climates: if you live in an arid climate like Arizona in the U.S. or San Miguel de Allende in Mexico you may not ever see condensation on the water tank regardless of other factors.)
  
  Conventional steel water pressure tanks
  
   that do not use an internal bladder to separate their air charge from the water in the tank will normally lose air by absorption into the water over time. The rate of air loss, if no leaks are present, depends on the amount of water used and on how well any automatic air volume control is working.
  
  A water pressure tank that has lost its air charge is called a waterlogged tank or water-logged pressure tank. We can add air back to the tank pretty easily (described below
  
  at WATER TANK AIR, HOW TO ADD) but we'll also want to know why the tank lost its air charge.
  
  

  Bladder type or "captive air" water tanks 
  
  do not normally need to have makeup air added. If you are experiencing water pump short cycling problems with bladder-type water tanks and the problem is not in the pump control or water piping, the problem may be traced to a failure of the bladder itself - a component that may be replaceable.
  
  See WATER TANK BLADDERS & CAPTIVE AIR for details.
  
  2. Not enough water in the pressure tank:
  
  If your water pressure tank never shows any condensation, perhaps that's because no water or not enough water is entering the water pressure tank.
  
  This is the opposite problem from a water tank that has lost its air charge. We've found this uncommon case (of no water in the water tank) when the tank was defective, the pipe into the tank was clogged, or the tank was overcharged with too much air pressure. If there is too much air in the water pressure tank, this problem is usually self-correcting - the excess air leaves the tank through the supply piping to the building.
  
  But if the entry to the tank is blocked, or 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 rock or move the tank. If the tank is heavy with water it does not move easily. Be careful not to jiggle and break a pipe!
  

• Water pressure surging at the sink or tub faucets:
  
  If you see the water pressure spurting or changing between good pressure and weak pressure every 5-20 seconds, the water pump is turning on and off to rapidly, and something's amiss in the system. Even if the total draw down cycle (from time the pump cut off until it cuts back on) is a minute, your system may be short cycling or close to it.


• Pump relay clicking rapidly:
  
  If the actual water pump or well pump is located in the well or outside in a well pit rather than inside the building, you won't hear the pump turning on and off.
  
  However at the pressure tank is a pressure switch which senses the water pressure and turns the pump on (at low pressure, typically 20 psi or 30 psi) and off at the end of the pump cycle (at high pressure, typically 40 psi or 50 psi). If the relay is clicking on and off every few seconds the pump is short cycling and something's amiss in the system.


• Effects of ambient air temperature
  
  on water tank and pump control operation are not normally any concern whatsoever, but in the off chance that your water tank is installed in an unusually hot or cold location, you'll want to review
  
  The mathematics to calculate exactly how much difference a given air pressure or air volume change makes inside a water tank is presented in our companion
• article WATER TANK PRESSURE CALCULATIONS

If your water supply problem is not described by the symptoms above the issue may with the building piping, fixtures, or the well's ability to deliver water over a sustained time - the well yield. In this case see the diagnostic guide starting

at WATER PRESSURE LOSS DIAGNOSIS & REPAIR or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

My water bladder tank lost air after 8 months - what's wrong?

@InspectApedia Editor , Hi thank you for your answer, and im sorry for my english is not my native language.

My tank have this type of bladder in picture my old tank was with a bladder like bicycle tires with valve above.

So you say this type of tank with this bladder should never ever lose air? Expect if there is a leak? Small hole in bladder or? Hole in tank.

I had checked my tank two day ago because i installed filter, I drained all system and water from pipes i measured air in tank with digital pressure metter 29 psi when i installed tank i added 38 psi air because i use 40/60 pressure switch switch settings..

To be more correct i can't accept it because is just damn 8 month old, i saw rust around the air valve. I added strengh to the valve bolt i used foam to check if air leak but i dont saw anything. Now i dont know if rust come from water drops condensation where i keep my tank to be checked again in coming month.

I can't find good tank in my country they all are chinese or from turkey cheap one
Sticker show tested at 217 psi precharged with 30 psi. Added 38 psi.

How many seconds should cycle last from 40/60 if you open faucet by end. How much should be because i concerned about pump On 2023-04-09 by blero

Answer by InspectApedia Editor -

@blero,

Your question contains several conflicting points - I'll try again to be more helpful.

You're quite right: from the factory, the water pressure tank is light, filled just with air.

At installation, the tank's air pre-charge pressure when the tank is empty must be 2 psi below the pump cut-in pressure.

So if your pump CUT-IN pressure is 38 psi then the empty tank with pump off should show 36 psi.

'm surprised that any residential water pump would normally fill a residential pressure tank in just four seconds.

If the tank is not water-logged now - which you want to confirm - then the tank, at 13 gallons - is quite small and perhaps too small for your application.

About "my bladder tank lost air after 8 months"

IF your water tank is one that uses an internal bladder (the subject of this page) then it should NEVER lose air. The bladder keeps water and the air pre-charge separate.

So if your tank has lost its air charge either the internal bladder has a hole or tear and needs replacement OR someone let air out of the bladder at the air charge valve found at or near the top of the tank.

by blero

@InspectApedia Publisher, hi i dont know now to which one you refering i purchased tank 8 month ago it was like this from begining. There is no water inside tank in air space because tank is light not heavy, a waterlogged tank are heavy because all tank is filled with water but what concern me from 60 to 40 psi gauge drop fast.

How many second need to drop from 60to40 psi to start pump
Thank you

by InspectApedia Publisher - water tank is waterlogged, missing its air charge

@blero,

It sounds as if your water tank is waterlogged, missing its air charge.

by blero

Hello my submersible pump filling so fast my tank in 4sec as my tank is 13gallon and i have set to 38air 40/60 switch and water empty fast. Pump is 1.1kw 1.5hp and can pump 20gallon in 70feet well my well is 45feet deep

I know i made mistake but this was before i started reading and learn. Now pump fill fast i think i need 74 gallon tank for my pump but they are to expensive.

Also my bladder tank lost air after 8 month from 38 to 29 is this normal. And the manometer gauge drop some psi after shut off

Advice needed

Thanks

by InspectApedia Publisher - a tank that uses a bladder should not lose air

@blero,

That is right, a tank that uses a bladder should not lose air.

So either your tank has a leak in its bladder or the tank is MUCH too small for the way you are using it.

I would expect 20 seconds to a minute of running water before the pump would have to come on, but if your water pressure is set very high that number may be smaller.

Don't worry about English. I'm writing to you from Mexico.

...

Continue reading at WATER TANK AIR, HOW TO ADD or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES. or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER TANK AIR LOSS FAQs - questions & answers about water tank air, posted originally on this page.

Or see these

Recommended Articles

• AIR VOLUME CONTROLS, WATER TANK used on bladderless water pressure tanks
• WATER TANK AIR, HOW TO ADD
• WATER TANK AIR HOW MUCH TO ADD
• WATER TANK AIR VALVE REPAIRS
• WATER TANK BLADDERS & CAPTIVE AIR
• WATER TANK DIAGNOSIS & REPAIR - home

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS & SPRINGS

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