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

On 2020-11-01 by (mod) - running toilet caused pump short cycling?

Thank you Ray.

I have mentioned the running toilet problem but perhaps I can give it more emphasis and visibility.

That's a particular cause of intermittent pump short cycling - pump seems to run for no reason - because people often don't even realize that a toilet is running - especially if it's running slowly.

WATER PUMP INTERMITTENT CYCLING

cites running toilets as the no. 1 cause of this problem.

But I hadn't considered that some readers may use the term "short cycling" or might even encounter pump short cycling also thanks to a misbehaving toilet flush valve or leak. I'll add that note.

To be clear: short cycling well pumps are due to loss of an air charge in the pressure tank.

But a running toilet can be the trigger - the use of water - that brings that pump behaviour to notice, and more subtle, a long-running toilet might, by using a lot of water, actually speed the loss of the air charge in a bladderless water pressure tank.

Other problems with a running toilet include frozen drains and even flooded drainfields.

On 2020-11-01 by Ray E - one of the toilets was running and calling for water.

First, these are great pages - thanks. You may want to add a comment to the beginning of the article (unless it is already there and I missed it.)

We were having short-cycling with our water pump, so I did method #3, but the short-cycling did not stop. So, I checked for any unusual water usage and sure enough, one of the toilets was running and calling for water.

Once the toilet was fixed, the water pump returned to its normal self. So, the comment you may want to add at the beginning of the article is for the homeowner to check to make sure that there are no out of ordinary calls for water that may be making the pump continually turn on to refill the water tank.

On 2020-08-11 by (mod)

Shani

Where is your water tank located, on what floor. It's a pump used to move water in your building or is your water supply by gravity?

On 2020-08-10 by shani

We have low water pressure in our ground floor
we have concrete water tank the water pressure is normal on first floor

On 2020-07-26 by Kathy

Our cistern pump was installed as “high pressure” pump with a tank with bladder. If I turned on the shower, it used to run for 20 minutes straight before turning off. Now it runs a minute and then shuts off for 30 seconds before repeating. I’ve looked at the tank and it’s heavy so I know it has water in it. There’s no condensation and the tank feels the same temperature from top to bottom.

On 2020-01-15 by Anonymous

Ronnie

You don't have to suffer such inconvenience. Just turn the system on, use water as you need, with one caveat:

IF you hear the pump cycling on and off VERY reapidly, such as just seconds apart, then turn it off so as to avoid damage.

Keep me posted

On 2020-01-15 by Ronni Bergman

Thank you for your response! I decided to turn pump power on, and quickly shower and do dishes, then go cut the breaker to pump again, so as not to harm pump or anything. This weekend, as funds allow, the husband will return from working out of town, and we can fully pressurize that tank. I just wanted to make sure I wouldn't hurt anything in the system, if I run it about 15 minutes a day, until then. I have a jug with a spout for the kitchen sink, so it's not too inconvenient for a few days. 😏 Lol. I sure appreciate the feedback!

On 2020-01-15 - by (mod) -

Ronni, your water system will work, but the draw-down water volume you will get before the pump turns on will be less than optimum.

I think things will work as follows:

Tank is at 28 psi air charge.
Pressure control CUT-IN is at 40 psi

As soon as you turn power on, the pump will turn on and pump up to 60 psi and turn off.

When you then turn water on in the home, compressed air in the tank, now at 60 psi, will push water out into the home;

Pressure in the tank will fall just to 40 psi and then the pump will turn on;

But because the pre-charge pressure is low, that turn-on will happen sooner than otherwise; long term that works the pump harder and could shorten its life.

Keep me posted.

On 2020-01-14 by Ronni Bergman

We had to replace our water tank with a used tank, and the pressure on that tank is 28 PSI empty. Our water pump is a 40/60 regulater. We have no way to put air in the water tank at this hour, what will happen if we turn the power back on and fill the tank up, and try to take a shower or do dishes? We need showers, but don't want to harm the tank or pump or switch

On 2018-10-22 by Anonymous

Yes sir I did took it off to blow compress air and clean it up

On 2018-10-22 - by (mod) -

Mark,

When you changed the pressure switch did you also make sure that the tubing or small diameter pipe that conducts water pressure to the switch was also clear? If not, check that.

On 2018-10-22 by Mark

I have a well been working fine. Recently I have had problems I first notice temporary loss of water pressure. I heard air bubbles and system lost pressure while not in use. So I pulled pump 180 ft installed check valve. Solved bleed off problem. But not when using water when pressure drops to 30 it should come on it sounds like it try’s but then when pressure drops to zero it kick on and goes to 30 then finally back to 48. Shuts off I changed the pressure switch and still won’t kick in at 30 psi like it should. What can it be. Only thing left is tank with bladder. Help

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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

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