Water pressure tank air pressure adjustment questions and answers.

This article series describes how to determine the proper air pressure setting in a bladder-type well tank, when, and how to actually change the air pressure in the water tank.

The page top photo shows the author testing the air pressure in a Well-X-Trol bladder type well tank.

Air Pressure Charge for a Bladder-Type Well Tank - Q&A

These questions and answers about how to set the air pre-charge pressure in a water pressure tank were posted originally at WATER TANK AIR PRESSURE ADJUSTMENT - be sure to review that procedure.

[Click to enlarge any image]

Watch out: for very high water pressure readings in your system. If the water pressure is over 70 or 80 psi your system there can be a risk of burst water pipiong or a burst water pressure tank.

Such an event can both flood the building and can injure anyone nearby. Check the maximum water pressure you're using against the maximum water pressure rating for the pressure tank itself.

That's why your water supply system should have

a WATER TANK PRESSURE RELIEF VALVE (separate article).

On 2021-12-07 by Inspectapedia Com Moderator

@Anonymous,

Good that you raised this air discharge because

Watch out: as I infer you already have worried: you do NOT want to send air through a tankless water heater or it may be burnt-up.

The problem is that there is an air source in your water supply system - it sounds as if the root problem may be a poor well flow-rate.

I would start with the diagnostics at

AIR DISCHARGE at FAUCETS, FIXTURES

Do keep us posted - we'll see what happens when you've looked at and tried the diagnostics there.

On 2021-12-06 by Anonymous

I have a Waterworker 20 gallon tank and jet pump with a 30/50 switch. When my tank pressure gets down to 34 or 35 my faucets start spitting air. I raised the switch cut in cut off to 40/60 but still have some air spitting when pressure lowers near cut in.

If showering the spitting will get so bad we shut off the faucet and wait until builds up. The worst of this is through the hot water side and we have a hot water on demand not a tank heater. What do you think?

On 2021-11-26 by Inspectapedia Com Moderator

@David,

Pressure is not determined by the pressure tank, but rather by your pressure control switch that turns your pump on and off.

From the factory typical residential water pump pressure control switches turn on at 20 or 30 PSI and turn off at 40 or 50 psi.

When installing a new water pressure tank or adjusting an existing one, the tank's pressure, with the water pump turned off and no water pressure in the system, is set to 2 PSI below the pressure control switch cut in pressure, for example 18 PSI or 28 PSI.

On 2021-11-25 by David

what should the standard air pressure be in a 20 gal holding tank

On 2021-09-28 by Inspectapedia Com Moderator - Pressure tank pre-charge considerations

@Tom,

More likely your gauge is inaccurate.

On 2021-09-28 by Tom

@inspectapedia.com.moderator,

Thank you! Since the cut-in switch is turning on at 32psi when the air pre-charge pressure is 35psi, I take it that the problem is with the switch.

All the best.

On 2021-09-27 by Inspectapedia Com Moderator

@Tom,

If I understand you correctly, I make your description as two pressure measurements, made at different locations

You said

"I am measuring the air pressure at only one location with one device; the air valve at the top of the tank using a digital tire pressure gauge. "

[I make this as measurement #1 at location #1 with device #1]

"The other measurement is the water pressure in the outlet pipe at the bottom of the tank and is measured with the water pressure gauge attached to the pipe. "

[Measurement #2 - presumably with a gauge mounted into a tee on the supply pipe]

It is the water pressure that drops to zero when the tank is empty. The pre-charge air pressure remains at 35psi. I hope this clarifies the situation.

If a tank is pre-charged to 35 psi and the pump is left OFF and you run water, water pressure in the system will fall to zero and the pressure in the tank, now measuring the air charge, will show 35 psi.

If the pump is turned ON and if your water pressure drops below the pressure control switch CUT-IN pressure (something hopefully above 35 psi, like 37) then the switch isn't turning on when it should - and is mis-adjusted or debris clogged, or defective.

On 2021-09-27 by Tom

@inspectapedia.com.moderator,

I am measuring the air pressure at only one location with one device; the air valve at the top of the tank using a digital tire pressure gauge. The other measurement is the water pressure in the outlet pipe at the bottom of the tank and is measured with the water pressure gauge attached to the pipe.

It is the water pressure that drops to zero when the tank is empty. The pre-charge air pressure remains at 35psi. I hope this clarifies the situation.

Thanks.

On 2021-09-27 by Inspectapedia Com Moderator

@Tom,

When you are measuring air pressure at two different locations on the equipment using different measurement devices it would be no surprise that your measurements with different. Difference could simply be the responsiveness of the pressure gauge.

On 2021-09-27 by Tom

@inspectapedia.com.moderator,

Again, thanks for the reply. I understand what you are saying about how the tank should operate. Nevertheless, my system behaves just as I have described and I do not understand how that is possible.

The air pre-charge pressure is measured at the air valve on the top of the tank using a digital tire pressure gauge. The water pressures are measured by a standard dial-type pressure gauge mounted on the water pipe about six inches from the outlet at the bottom of the tank.

I understand that, with a pre-charge pressure of 35psi, the water line pressure gauge should not read less than 35psi. However, my gauge drops all the way to zero when the tank is empty, with the pump cut-in switch tripping at 32psi.

Before I reduced the pre-charge pressure from 39psi to 35psi, the pump cut in switch was tripping at 37psi.

Moreover, the water pressure gauge is new. (Perhaps it is defective?) In any case, I am concerned that something is seriously wrong with this system and have no idea how to set it right.

Thanks.

On 2021-09-27 by Inspectapedia Com Moderator

@Tom,

I would like to be helpful but I really don't understand this situation as it has been described.

If a water pressure tank is pre-charged to 35 PSI, you will never see 32 psi on the pressure gauge for the tank.

When it's completely empty of water the tank would be sitting at 35 PSI, the air pre-charge level.

And while it's possible to adjust the pressure control switch to change the cut in, cut out, or to shift the entire range up and down, if you haven't touched the pressure control switch and all you've done is change the pressure tank air pre-charge, then you are not changing the control switch settings.

Generally where people get in trouble is when they set the pressure tank air pre-charge to a higher pressure than the pressure control switch cut in setting.

In that case since their system pressure never will fall to the cut in level the pressure control switch will simply never turn on the pump.

You might want to comment about where and how you are measuring the pressures you report.

It's possible you were measuring in different places, or that your pressure control switch is too far from the water pressure tank itself.

Keep in mind also that this is not lab great equipment - it's not precise.

On 2021-09-26 by Tom

@inspectapedia.com.moderator,

Thanks for your reply. What appears to me to remain a problem is that, with the pre-charge pressure set to 35psi, the cut-in pressure has changed from 37psi to 32psi.

Other than that, the pressure dropping as the tank is drained is normal until the new cut-in point of 32psi is reached, at which point the pressure drops instantly to zero. What I would like to know is if this behavior is normal for this type of tank or, if it is not, is there any danger in operating it this way?

Thanks.

On 2021-09-23 by Inspectapedia Com Moderator - correcting the pressure tank air pre-charge to set it to 2 psi below the pressure switch CUT-IN pressure won't change the pressure switch settings

@Tom,

Changing, or we should say correcting the pressure tank air pre-charge to set it to 2 psi below the pressure switch CUT-IN pressure won't change the pressure switch settings but it will change (and correct) how the pump operates.

It sounds as if you've not got things operating correctly, though I may have got lost in your posting.

With the pre-charge set to 35psi, 2psi below the cut-in pressure of 37psi. , the pump should turn on at 37 psi and cut of at your cut-off pressure setting of around 60 psi.

Remember that the pressure switch is not a lab-grade precise control; so it may be a 1-4 psi "off" of the settings you tried to achieve. There is also some variation in pressure readings as the pressure may surge when the pump first turns on, and it may drop slightly when the pump turns off.

The rest of the behaviour you describe sounds normal. E.g. the pressure continues to drop if you drain the tank when the pump is turned off.

On 2021-09-23 by Tom

We've just had a new pressure tank installed at our off-grid home and have encountered some puzzling behavior.

Our well pump is run by a gasoline-powered generator that we only use when we need to pump water from our deep well. The original system was installed in 1989 and, when the old pressure tank stopped working, we purchased a new Water Worker 62 gallon bladder tank (HT62B).

The system is set up for 60/40psi operation and with the old tank we could draw water all the way until the tank was empty before refilling it, if we chose to do so.

We hired a licensed plumber with experience in deep well systems to install the new tank. The new tank was supposed to have a pre-charge pressure of 38psi.

All went normally with the first tank filling. The water pressure gauge rose steadily from zero to 58psi, at which point the cut-out switch disconnected power to the pump.

As the well system had not been used in some time, I wanted to run a few tanks of water through it before collecting a sample for the county health department. While draining the tank through the drain faucet located near the base of the tank, I watched the pressure gauge needle move slowly downward, as it should.

The first anomaly occurred when the gauge reached 37psi. At this point, there was a "click," the water flow abruptly stopped, and the pressure gauge needle dropped instantly to zero. (I presume the "click" was the cut-in switch operating but, as there was no power to the system, the pump did not engage.)

Upon closing the drain valve I encountered the second anomaly; the pressure gauge needle began rising slowly, and finally stopped at 37psi.

the drain valve produced a small amount of water and the pressure gauge needle dropped quickly to zero.

In the course of draining the tank, I recovered about 16-1/2 gallons of water.

I was able to confirm that the tank was empty by pressing lightly on it with my fingertips near the top, which caused it to easily rock slightly.

I had read that the pre-charge air pressure should be 2psi lower than the cut-in pressure switch setting, so I checked the pre-charge pressure with a digital tire pressure gauge. The reading was 39psi.

Thinking the high pre-charge pressure might be the source of the odd behavior, I let air out of the tank until I had the pressure at 35psi, 2psi below the cut-in pressure of 37psi. I then opened and closed the drain valve to reset the water pressure gauge to zero and started the pump to refill the tank.

The third anomaly occurred as soon as the pump started when the pressure gauge needle jumped from zero to somewhere in the 30s-psi range.

From that point on, the gauge needle rose slowly and steadily to 58psi, at which point the cut-out switched turned the pump off.

The fourth anomaly happened when I was again draining the tank (with the electrical power off). This time, water kept coming out of the tank as the pressure gauge needle passed the 37psi mark. I recovered about 20-1/2 gallons before the cut-in switch clicked at 32psi, the water flow stopped, and the pressure gauge needle dropped to zero.

Thinking that if the cut-in pressure setting changed, that the cut-out setting might also have done so, I refilled the tank. The cut-out occurred at 58psi, the same as before.

At this point, I am completely confused, as I don't see how changing the air-pressure of the tank pre-charge can change the pressure setting of the cut-in switch. I don't want to make any more changes to the system settings until I either understand what I need to do to get this tank working correctly, or if I need to hire a professional to come sort out the problem.

Any advice will be much appreciated.

On 2021-05-22 by danjoefriedman (mod)

@Pete,

How to Adjust Water Pump Pressure: The detailed, step by step procedure for inspecting and adjusting the water pressure control switch is discussed in detail

at ADJUST PUMP PRESSURE CONTROL - https://inspectapedia.com/water/Pressure_Switch_Nut_Adjust.php

(above on this very page)

You'll see that on most pressure control switches there are two nuts to adjust: a larger one and a smaller one.

Complete details of what these adjustment nuts do and which way to turn them are found

at PRESSURE SWITCH NUT ADJUSTMENTS

https://inspectapedia.com/water/Pressure_Switch_Nut_Adjust.php

Please take a look and don't hesitate to post a question or comment as needed.

On 2021-05-22 by Pete

How do you increase the pressure setting on an existing water pressure tank

On 2020-12-13 - by (mod) -

Joey

The best place to start, as it's a most-complete list of diagnostic questions and steps, when there is weak or poor or no water pressure, is at

WATER PRESSURE PROBLEM DIAGNOSIS TABLE https://inspectapedia.com/water/Water_Pressure_Table.php#

On 2020-12-13 by Joey hagen

My water comes out of fauset very slow then nothing....if I turn the main line to off it builds then it flows food for a hour....my pump is very very quite...it's never that quite. Vibrating. Well flow mostly?

On 2020-11-06 - by (mod) - pressure won't get over 30 psi

Brian

Earliest possible to increase the settings on your pressure control switch to get a higher pressure just as you suggest. Take a look in the article index and you'll find our articles on how to adjust the pressure control.

On 2020-11-03 by Brian P

The pressure in the system was too low on the 2nd floor, shower especially. First issue.. the tank is in the basement and when I checked it, it had 0psi of air in it, I pumped it up to 28PSI or so. The old gauge was dead so I installed a new one. I have a 4-5 yr old 30\50 switch, looks ok.

Is it possible to run my 30/50 switch as a 40/60 or do I need to replace it for a 40/60? I tried adjusting the switch all day yesterday to increase the pressure that is a lot better already.

Today it looks like it's working between 30/53 or so. I can adjust the high end to 60 but the low end seems stuck at 30PSI or so.

On 2020-09-23 - by (mod) -

Jay

Thank you for the comment

On 2020-09-23 by Jay

If your tank is set for 38 psi and your cut in pressure is 30 psi then your tank should be set for 28psi (2psi below cut in pressure) when there is no water pressure in the tank.

Don't forget to use an accurate pressure gauge to measure the air pressure on the tank.

On 2020-09-23 - by (mod) -

Jay

Thank you for the comment

On 2020-09-23 by Jay

If your tank is set for 38 psi and your cut in pressure is 30 psi then your tank should be set for 28psi (2psi below cut in pressure) when there is no water pressure in the tank. Don't forget to use an accurate pressure gauge to measure the air pressure on the tank.

On 2020-09-10 - by (mod) -

Tammy

The pressure tank air pre-charge does not determine the water pressure at your faucets itself; rather that's done by your water pump.

The water tank air pressure pre-charge should be set to 2 psi below the water pump CUT-IN pressure.

To adjust the pressure control switch itself

see WATER PRESSURE CONTROL SWITCH ADJUSTMENTS

and to find the instructions for your specific switch

see WATER PUMP SWITCH INSTALLATION MANUALS

On 2020-09-10 by Tammy

We do not have good pressure coming out of any of our faucets.My husband checked pressur on bladder and it was 33psi so he added 2 so it is now 35psi.

It is recommended tobe set at 38psi. How much of a difference will that 3 pounds make in terms of the pressure we get?

On 2020-09-02 - by (mod) -

Gl

It sounds to me as if your water pressure tank is waterlogged. Take care to be sure that you've drained water and pressure from the tank before you set the air pre-charged to 2 PSI below the pump cut in pressure setting.

On 2020-09-01 by Glc482

Hello, I was having problems with my water shutting off when using either of my outside hose spigots.

It was suggested by a employee at local plumbing supply , that I should check the pressure at the water pressure tank. I checked and it was higher than the cut-in pressure on control switch. He also suggested I turn off the electric to pump and drain the whole water tank
, which I did.

I then put 28 psi into pressure tank and turned on pump to fill tank back up. Pressure then rose to 60 on pressure tank.

I bleed of pressure back to 28. Everything thing seems ok, except anyone s faucet is turned on, the pump immediately turns on and even though pressure rises to 50 quite quickly, take a few minutes to shut off. Is there a possible link with the fact that water pressure was so high after refilling tank,?

Added note: pressure switch settings are at 30/50.

On 2020-07-20 - by (mod) - always opt for the simplest explanation, but ... 2 common causes of low water pressure in the morning

Ns

Occam's razor argues that we should always opt for the simplest explanation, so I am embarrassed to say that I suspect two things are going on at your property instead of just one. Is possible that you have a slow leak in the well piping or at the foot valve that is losing water pressure overnight.

Actually a leak anywhere in the system could cause that problem, even a running toilet that can be hard to detect.

If in addition pure water pressure control switch is defective, such as having burned contacts or debris clogged sensor Port then it may be slow to respond to a drop in water pressure until the pressure gets well below the cut in level.

You could try tapping the pressure control to see if that causes it to turn on when the water pressure is quite low.

Of course check to see whether or not the pump is already running. But you may need to replace the switch.

On 2020-07-20 by Ns24601

Well system, when we get up in the morning there's low water pressure.

If I run the water for 15-20 seconds and then turn off the fixture, the next turn on (within a few seconds) will be full pressure. No air burping, no banging or any other noises at the faucets, and had everything checked a month ago when I moved in.

Where do I start checking? I've had experience at other houses where the pressure builds as you run the water but haven't seen this one.

On 2020-04-25 by Mikepointer6426

My pipes are humming so I think its my bladder tank

On 2020-02-28 by (mod) - pump won't reach cut-off pressure

Jonny

That pump stopping at 25 psi and kicking back on could be itself triggered by a leak in well piping combined with a pump that can't get ahead of the leak or for other reasons can't reach the cut-off pressure.

Let's start with the diagnostic suggestions

at WATER PUMP WONT STOP RUNNING

take a look and let me know what you think

On 2020-02-28 by Jonny

Ihave a plumbing question, I have a 3/4 jet pump hooked up to a 36 gallon pressure tank , 500 gallon water tank , pump kicks on but will not reach shut off pressure at 40p , pump stops at 25psi for a few seconds then kicked back on , it keeps repeating this .seams to thermal overload, pump is new, pressure tank is new , all new plumbing in pump house , no leaks visible.

Any ideas why pump will not reach pressure , house is getting a little water but it just runs out and pump will not kick back on until safety switch lets it . If you have any idea it would be greatly appreciated, thanks

On 2019-04-11 - by (mod) -

Sorry Bobby but I don't understand the question

On 2019-04-11 by bobbycampbell

my.new.tank..pressee.swich.20.40.what.air.preesee.be.my.gagag..go.up.donw.when.water.running.the.cut.of.then.go.up.done.tell.you.cut.it.of

On 2019-02-02 - by (mod) - pressure gauge is stuck or jammed

Kevin:

1. Make an independent measurement of water pressure - say mounting a gauge at a washing machine or outdoor house bibb to get the actual pressure - as your gauge could be stuck

Consider that if the pressure is really 38 psi and you've got a 30/50 pressure control then 30 psi is the CUT-IN pressure and the pump shouldn't start until pressure drops down to that level. (That's why I suspect a stuck gauge and wrong pressure reading)

2. When a pump is short cycling that's usually a water-logged (lost air charge) pressure tank -

see WATER PUMP SHORT CYCLING - home

For causes such as running water, a leak somewhere

But the no-water flow at all is worrisome:

3. Confirm that there are no closed water valves between pressure tank and building.

On 2019-02-02 by Kevin

my pressure switch reads 30/50psi, my bladder tank has 38 psi, with no water flow, my pump starts and stops every 60 seconds, what should I do?

 

On 2019-02-02 by (mod) - how long will it take to use a bicycle pump to pressureize a water tank to 18 psi?

Pat:

Thanks for asking a great question that I generalize as follows:

How long will it take me to get 18 psi of air pressure into my water pressure tank if there was no air to start with and if I use a good quality bicycle pump?

About 15 minutes of pumping time to get 18 psi of air into a 30 gallon water tank that contains no air to start with - more or less, as I will explain.

The true answer ... as Mark Cramer says ... depends.

It depends on

- the size of the pressure tank

- how much water is in the tank and at what starting pressure

- the size, capacity, and pumping volume - per stroke - or pumping rate of your hand pump - shown above, a Blackburn floor pump or bicycle pump sold by Eastern Mountain Sports and others (ems.com).

- how fast you operate the hand pump and how long you can keep it up without pause

Here's a data point: a standard "floor pump" for bicycle tires, that is a pump that stands upright on the floor, that you stand on, with a T-handle can pump about 300 cc's per stroke - and can pump to 160 psi.

If the ENDING volume of air in a 30 gallon water tank will occupy half of the tank's total volume at 18 psi, that's a 15 gallon space filled with air, that's about 57 liters of air. That's 56000 ccs of air.

If your pump pushes out 300 cc's per full stroke, the number of strokes (S) required is

56,000/300 = 187 strokes.

If you pump like mad and can manage one pump stroke every 5 seconds that;s

187 x 5 = 933 seconds or 15 minutes of pumping, assuming you are starting with zero air in the tank.

On 2019-01-29 by Pat

Water tank read no pressure. How long does it take to hand pump 18 psi in it.

On 2019-01-13 by (mod) - when i turn water on it run fast then slows down

I see that phenomenon myself at some water systems in which you open the tap and for a brief moment you have good pressure or flow but it rapidly falls off to a much slower rate.

Typically that's because you have a limited flow rate from your Pump and Well system.

What happens is when you stop running water the pump continues to run and pumps up to the cut out pressure. The duration of the drawdown cycle at good pressure will be increased if you increase the air charge in your pressure tank. Try that first and let me know how that works for you.

On 2019-01-13 by joe

when i turn water on it run fast then slows down

On 2018-12-31 by (mod) -

Gart

I don't know what record you are referring to so I can only give a general answer. If you've lost the air charge from an internal bladder-type water tank I suspect you've damaged the valve or the tank. Perhaps you can attach a photo to a comment to show me what we are discussing.

On 2018-12-31 by Gary

What happens if you screw down the bracket to tight on top of the bladder tank and sir comes out

On 2018-11-25 by (mod) - can't read the pressure gauge on the water tank

J John,

No a gauge that's not working such as a pressure gauge you showing your photo will not cause low water pressure.

However there is a possible connection between and low water pressure. That would be debris clogging if there is silt or mud in your water supply.

That fine debris can clogged both the water entry port on the pressure gauge and the water entry port on the pressure control switch.

Watch out: However your leaky water tank pressure gauge - shown here - should be replaced before it bursts and floods your utility room.

For details of how to replace your leaky water pressure gauge

see WATER TANK PRESSURE GAUGE

On 2018-11-25 by John

My psi is at 60 and I can't read the Gage it's to rusty to read will that cause low water pressure?

On 2018-11-13 by (mod) -

Tim: depending on water pressure tank brand and model there may be more than one place where you can attache a tank tee or other plumbing fittings.

Check the manual that came with your tank so that we know what that plug is: an attachment point may need to have an actual pipe plug installed, or a something else.

On 2018-11-13 by Tim

I purchased a new pressure tank. it has a black plug in the bottom. does this plug have to be removed?

On 2018-10-27 by (mod) -

Always start by setting the pressure tank air charge to 2 psi below the CUT IN pressure

On 2018-10-27 by Anonymous

should I increase the cut in pressure on my jet pump first or should I add air pressure to the tank first - the pump is not at the original pressure - presently cutting in at 25 p.s.i.

On 2018-10-27 by (mod) - Always start by setting the pressure tank air charge to 2 psi below the CUT IN pressure

Always start by setting the pressure tank air charge to 2 psi below the CUT IN pressure

On 2018-10-27 by Anonymous

should I increase the cut in pressure on my jet pump first or should I add air pressure to the tank first - the pump is not at the original pressure - presently cutting in at 25 p.s.i.

On 2018-10-07 by (mod) - water suddenly stops entirely for a few seconds and then comes back on

Gary

We have a diagnostic article for the condition you describe,

at WATER PRESSURE INTERMITTENT LOSS https://inspectapedia.com/water/Water_Pressure_Comes_Goes.php

that will be more complete than an off-the-cuff reply here. Please take a look, try those suggestions, and please do let me know what happens and what questions remain.

Often, however, the problem is simply a debris-clogged pressure control switch.

On 2018-10-07 by Gary Thompson

My tank air pressure reads 52lbs.!! My cut in pressure is about 38 lbs.

At times when we air using more water (showering and running washing machine etc.) the water suddenly stops entirely for a few seconds and then comes back on.

What should I look for? I know the air pressure is too high but I don't understand why the water cuts off entirely.

Should I just drop the air pressure to about 36lbs. and see what happens? Any other suggestions are appreciated of course...

On 2018-09-30 by (mod) - How do you empty tank under house so you can remove it

Marty:

Turn off power to the water pump or well pump;

Connect a garden hose to the tank drain and run that outside.

Open the tank drain

Open one or several faucets nearby to let air flow into the system as water drains out of the tank.

On 2018-09-28 by Marty

How do you empty tank under house so you can remove it

On 2018-09-24 by (mod) -

Tom

Water pressure tanks are sold uninsulated. However there are removable insulating jackets that are sold as a separate product.

On 2018-09-24 by tom

can you get a tank all insurlationed

On 2018-08-14 by (mod) -

it sounds as if your well is running out of water

On 2018-08-12 by Larry

Water pressure drops when using shower then comes back back up. Water does not drop in the cistern but I hear a lot of air at the pump above the expansion tank. Location of pump in a pit outside.

On 2018-07-14 by Here 2 learn

..pumps comes on and off very rapidly till I shut off pump at breaker.

On 2018-07-14 by Here 2 learn

Have a pump with 30 cut on/50 cutoff pressure switch 20 cut on/40 cutoff and water pressure tank set at 28 psi. After tank is filled, pump comes on and off.

Any solutions?

On 2018-06-27 by (mod) - 2 PSI BELOW THE PRESSURE CONTROL SWITCH CUT-IN PRESSURE

Anon

The article WATER TANK AIR PRESSURE ADJUSTMENT (and other experts) recommend setting the air pressure in the water pressure tank (bladder type or also bladderless tanks) at

2 PSI BELOW THE PRESSURE CONTROL SWITCH CUT-IN PRESSURE

So if your pressure control switch turns on your water pump at 30 psi, you would set the water tank's air pre-charge to 28 psi.

Watch out: be sure that you set the tank pressure with the pump turned off and all water pressure relieved from the system.

On 2018-06-27 by Anonymous

how much air pressure bo you put into a 20 gallon bladdertank

On 2018-05-17 by (mod) -

From the article WATER TANK AIR PRESSURE ADJUSTMENT

Set the air pressure in the empty water tank to 2 psi below the well pump pressure switch cut-in pressure.

On 2018-05-17 by Anonymous

, how much air pressure do you put into a 30 gallon bladder tank

On 2018-03-13 by (mod) -

It's normal and correct for the pressure in the water pressure tank to be the same as the pressure in your water piping system. They are connected common and that's exactly how the system functions.

Put another way, the water pressure tank doesn't produce water pressure is simply delivers water at the system pressure, with pressure falling until the pump turns on. It's the water pump that produces water pressure.

If your water pressure in the building is low it could be that you need to adjust the pump pressure control switch settings to a higher number. If by low water pressure you mean that the flow is poor the problem could be a different one such as clogged water pipes or blockages in vowels or elbows or even something as simple as clogged faucets strainers.

In our index at

https://inspectapedia.com/water/Index_Water_Supply_Systems.php

You'll find a series of articles on diagnosing and improving poor water pressure or flow.

On 2018-03-13 by Seth

I have low water psi in the house . House has been empty for a couple months . Getting ready to move in and I find this ...

My air bladder tank always has the same air psi as the water psi . So if I run a faucet and water psi gauge drops to 30 psi , my air pressure says 30 as well when I check it with a tire gauge . WhTs this mean ? Any help would help please

On 2018-03-03 by Barb

We have wellxtroll air pressure tank. Due to high winds we lost power for several hours. I tried to restart it at the controll switch.

The gauge would not adjust and go anything above zero. I double checked the electrical control box to make sure there was not a flipped switch. All were on. Any suggestions?

On 2018-02-12 by (mod) -

I would check first for and replace a debris-clogged pressure switch that is not properly sensing water pressure - also check for a clogged pressure gauge and replace that too if needed. A bigger tank or changing tank size won't affect an improper pressure condition.

Keep in mind that if truly a tank is being pressurized above its rated pressure that's dangerous as the tank could burst and injure or kill someone nearby.

On 2018-02-10 by Larry

I've never seen this before I was in well drilling for 12 years, so in a standard 202 size bladder tank, my buddies water tank was building air pressure in tank when building on switch, like 40-60 switch it was like 70 psi air in tank, so it was making the switch Serge on off ...my ? If he has 1hp pump in his well like he does, should it be a bigger bladder tank put in

On 2018-01-02 by Robert Jackson

Only water tank pressure tank for bladder or the set pressure

On 2017-11-04 by (mod) -

No, Gary, those external threads on the Schrader valve or simply to mount the cap and a knot that secures the valve stem in place.

The pin in the center of your air hose head or air pump head should push down the pin in the center of the valve to permit air to pass

On 2017-11-04 by Gary

Mt tank appears to nor have a Schrader valve. Looks like threads to screw on into. Trying to add air. Could it be, you need to screw valve into, put air in then remove it...would need some kind of check valve there?

On 2017-10-14 by Anjana

Due to low pressure of tank our purifier is not working . how to increase pressure

On 2017-09-05 by (mod) -

Bo

If we are talking about a submersible well pump, in the well, under water in the well bore, and if are getting air discharge at plumbing fixtures, then I'd follow the diagnostic and repair suggestions found by using the search box above to find our article

on AIR DISCHARGE at FIXTURES since there are several possible causes.

On 2017-09-05 by bo crawford

i put a submerp pump in it work fine for about 5 days not when the pump turn on when you areuseing it it has air in it i cant fine anything wrong and i check it at the tank and it has air in the water till it fill up then it is alwrigh

On 2017-07-09 by (mod) -

Great question, Anon.

Set the water pressure tank air pre-charge to 2 psi below the CUT-IN pressure of your water pump. With a factory-set store-bought pressure control switch the switch CUT-IN/CUT-OUT pressures are typically 20/40 psi or 30/50 psi, so the tank's pre-charge woudl be 18 psi or 28 psi.

On 2017-07-08 by Anonymous

How much pressure does my pressure tank need before installing

On 2017-07-06 by (mod) -

Janice,

I'm relieved that you were smarter than the guy who was trying to bamboozle you into a new well. What a dope.

The remaining symptom you are describing sounds to me as if there is a bad foot valve.

If a foot valve is leaking but there is power to the pump the pump will periodically turn on and recharged the pressure tank. But when there is no power enough water leaks out of the system and back into the well that you can lose water.

On 2017-07-02 by Janice McFadyen

Hi, My well provided plenty of water for my home and my rental (manf. home). Last year I sold the rental and had the water lines cut to that home. My well/pump became touchy and Home Shield sent repair persons. I am a senior citizen and a widow. Immediately this company told me that I needed a new well...

.I may be old, but I do have most of my brain and had googled characteristics of a well running dry and my well presented none of these things.I told him that the pump was old...over 25 years and finally begged him to put in a new pump. The pump worked fine until the power went off during Matthew. It took almost 5 gal. of water to prime.

Worked fine until I went away for a month...same deal had to prime. Today the power went off for approx. 30 min. and when I turned on the water, it sputtered like it does in my motor home after it has sat. Once I blew out the air, all was fine.

I have noticed when I turn on the yard sprinkler, the pump runs most of the time that the water is on. I went into the pump house and touched the pump which was a little hot. Next I tried to move the holding to see if it was empty t and it was easy to move. Both the tank and bladder were new less than 2 years ago.

I always tell the pump/well folks that there were two homes connected to this well and that the other home had the connections cut.

A couple of questions...could there be water leaking from the cut connection and/or does the holding tank need air?

Pressure is at about 55 lbs. when pump is working. I live in a very sandy area and I don't think that the well is that deep

. It is not a submerg. well and I only have 2 in. pipes. I can't think of anything else to ask/tell about this situation. Please help me and thank you in advance for doing so.

On 2017-06-28 by Pete

What is the typical service life for the bladder in a fiberglass tank?

On 2017-06-26 by GC

Tank pressure at 18 lbs. Factory switch is a 20-40. Problem is low click on occurs at 30 lbs. Have attempted adjusting pressure switch limit nut to no avail. Any thoughts? Thanks

On 2017-04-09 by (mod) -

AJ

Please use the search box just above to find our article discussing "WATER PUMP RUNS for NO REASON" or "INTERMITTENT PUMP CYCLING" to see the usual causes and cures. Air pressure changes in the tank won't fix this problem. More likely there's a leak in well piping, a bad foot valve, or a running toilet.

On 2017-04-09 by AJ

We hear the piston pump start at times when no water is running. We are using a piston pump, can you tell us what would be the average air pressure in tank so my dad can stop playing with air pressure in the tank.

Does the pressure self regulate?

On 2017-04-03 by (mod) -

Thomas,

The pressure in a water tank will increase when the pump runs, PROVIDED you set the starting air pressure in the tank to 2 psi below the pump cut-in pressure.

With your pre-set pressure at 40 psi in the tank, unless your pressure control switch is turning on the pump at 42 psi, it won't run.

On 2017-04-03 by Thomas

With water bladder tank drained and air preasure set to 40psi will tank increase psi when water turned back on

On 2017-03-01 by (mod) -

Glen:

If you are using a 30/50 cut-in/cut-out pressure control switch then when the pump turns off the tank pressure will be close to 50 psi. It may drop slightly below that when the pump stops, depending on the pump's technical properties and depending on the rest of the plumbing system to which the tank feeds.

On 2017-02-28 by Glen

What is the full tank pressure for a 50/30 pressure

On 2017-02-26 by (mod) -

Perhaps a tub conducting pressure to the switch is clogged or
you could have a loose or corroded electrical connection in the pump circuit or controls.

On 2017-02-26 by Charliel L.

The presure drops to zero sometimes then picks up right away. I have instaled a new presure switch but that did not help. I set the cut in higher but that did not help

On 2016-12-24 by Anonymous

How much air do you put in the pressure tank

On 2016-12-05 by R Conner

Our system shuts down within one minute after running water outside while filling water tanks for livestock. It throws an on-off switch. We have to flip the switch to run water for a short time before it flips the switch again.

We do not have this trouble inside the house while using the shower or faucets, although, we sometimes have air in our house lines. The outside lines do flow quite a bit more water when on. The system is 12 years old. This trouble started about a year ago.

On 2016-11-21 by (mod) -

RE-Posting on new version of this article:

Question: valve on pressure tank is leaking air when I take off the cap - is this normal?

2016/11/21 John said:

Just shocked well , after flood. Air presure valve was removed ,reinstalled.valve leeks air without airvalve cap. Is this normal?

Reply: no. tighten or replace the valve stem core.

No, John. We shouldn't see water (nor air) leaking from the air valve.

Stop by your auto parts store, pick up a tire valve replacement tool - you'll need this to un screw the actual valve core from the stem. Try removing, cleaning, and replacing the existing valve core, or just install a new one.

Watch out: on some well systems, particularly those using a submersible pump and an in-well snifter valve, the above-ground snifter valve core spring is a softer one than is used in car tires since it needs to open and close at a lower pressure range.

If the auto type replacement core gives trouble later (such as inadequate control of the air volume in a pressure tank that does not use an internal bladder) then a different core could be needed.

If your pressure tank is one that uses an internal bladder, a standard automotive valve core will work fine.

Watch out: if WATER is leaking out of the air valve on a tank that uses an internal bladder, then the bladder is leaking.

Reader Comments

(Apr 26, 2011) Dumby Dan said: What a LIFE SAVER this article is!!

(Feb 1, 2014) Divechickie said: Wow. What a great article. I'm in the caribbean with no expertise available. This article is awesome, informative and so helpful! Thank you!

Reply:

Thanks for the nice note, DC. We also welcome questions & content suggestions. Daniel

Question: what should normal setting be on pump switch and comparative preasure on air bladder

(Apr 19, 2016) ray said:

what should normal setting be on pump switch and comparetive preasure on air bladder

Reply:

The article WATER TANK AIR PRESSURE ADJUSTMENT states

Set the air pressure in the empty water tank to 2 psi below the well pump pressure switch cut-in pressure.

Bleed air pressure out of the water tank, or add air pressure into the water tank, until the tank pressure.

For example, if your well pump pressure control switch is set to "cut in" (start pumping water from the well) at 30 psi, then set the pressure tank to (30 - 2) = 28 psi.

The pressure produced by the pump will be found the same in the water and in the air in the tank.

Sorry if there was some confusion but the article is correct. 2 psi BELOW the cut-in.

You're right that if a pressure tank's air charge is set to anything ABOVE the pressure switch CUT-IN pressure then the pump will never turn on.

Question: proper pressure tank air pre-charge setting in psi

(June 13, 2016) Neil said:

Error...You have 'above' instead of 'below' in this paragraph...

If the water tank bladder is un-damaged, air pressure in the bladder will push water out of the tank completely leaving some air charge inside the bladder (unless you inadvertenly let air out of the bladder through the air valve).

In a bladder type water tank with proper pressure adjustment, when all water has left the tank you'll see air pressure at 2 psi ***above*** the pressure switch cut-in setting.

Even if the tank air pressure is too low, you should still see some air pressure at the tank air

thanks for info, very helpful, keep up good work

Reply:

Thank you Neil. Sharp eyes. I'll fix that right away. I appreciate all the editing help we can get and more that you took the time to write.

The air charge in a water tank should be 2 psi BELOW the pressure-switch CUT OUT psi setting.

Question: pump cycles on and off

(July 18, 2016) Craig said:
I have had a well system for 12 years and have never touched it or had issues with it. This morning the pump started cycling on and off

so I went to the pressure tank and sure enough, the pump was kicking on and off every couple seconds with a faucet turned on.

I turned the pump off so as not to burn the pump up and drained the tank of water then checked the precharge pressure and it was at 48PSI with a pressure switch of 40-60 PSI.

I drained air out to 38 PSI and the system seems to be working right now. My question is what would cause the precharge to get so high? The system worked fine for 12 years and I changed nothing

Reply:

Good question, Craig. If this is a tank with an internal bladder the bladder may have a small leak.

(July 18, 2016) Craig said:
How would I find out if it has a small leak? If I drain the precharge to zero, I should get water out if this is happening. Right?

(mod) said:
Not necessarily; a leak that sends water out of the bladder and into the air space is often "one way" - you can drain the tank but some water remains in the air space. If the tank has been emptied but remains heavy that's a clue.

(July 18, 2016) Anonymous said:
What I'm saying is there should be water in the airspace that will come out if you take the air valve(like a tire air valve)out and put water pressure from the pump to the other side...This should push any water out if there is any, correct? How else do I find out if it is leaking?

(mod) said:
Unfortunately the water will be low in the tank and the air will be uppermost in the tank. By the time you see water coming out of such an air valve the tank is totally fuill of water.

If you can gently shake the tank (without breaking pipe connections) and it feels light, then it's not carrying (much) water.

if the pressure rises again after you set it down, that's a suggestion that the situation I describe is occurring

(July 18, 2016) Anonymous said:
"if the pressure rises again after you set it down", I'm not sure I understand

(mod) said:
The pressure in your tank rose above a proper tank pre-charge pressure. Some defect caused that.

Adjusting the pressure back down to 2 psi below the CUT IN pressure is a good step but that won't fix whatever caused the pressure in the tank to increase. A common cause of that increase is a small leak in the tank bladder.

Other causes of rising pressure exist of course, such as a mis-adjusted or tampered-with pressure control switch or one that's defective or clogged and so fails to shut off the pump when it should.

Be sure your tank has a pressure relief valve.

Question: water pressure cycles between strong and weak

(July 21, 2016) quin said:
Not to sound too dumb, but I live in a condominium complex with 12 individual rooms (apartments). When I turn on a faucet in the bathroom or kitchen sink in my particular apartment the water pressure goes strong then weak then strong then weak. It is not a consistent flow. Can anyone provide a bit of info as to why? What is happening and how I may be able to fix it? Thanks!

Reply:

Quin, not sounding dumb at all;

A cycling water pressure (actually flow rate) sounds to me as if there is a bad pressure regulator somewhere in the system OR a pump is short-cycling on and off; if so, the fix for the former is most likely at the water pressure regulator. Check with a few neighbours; if they too have the problem that'd be diagnostic and would indicate that it's not specifically a problem in your condo.

Question: Just today I had my water pressure drop significantly. It does recharge but drops again after about 15 seconds.

2016/07/28 Scott said:
I have a pump in my well with a pressure tank set up at my home. I've owned the house for twelve years and have never had a water problem. I change my water filter several times a year as there is some rust. Just today I had my water pressure drop significantly.

It does recharge but drops again after about 15 seconds. I looked at my pressure gauge and watched as it rose to over 100psi before shutting off then go down to nearly 0 before kicking the pump on again. Then it would just go to 60 ad seem fine until faucet was turned on again. Is it my pump control switch or a bad pressure gauge? Pretty frustrating for me, hope you can help.

Reply:

Watch out: 100 PSI is dangerously high: it sounds as if your pressure control switch is not working.

IF that pressure is really occuring you could blow out a pipe or tank or control, not just causing a flood but inujring someone.

Search InspectApedia.com for WELL PUMP SHORT CYCLE CAUSES to read the less frightening diagnosis and repair steps.

On 2015-05-26 by pressure trouble

I had a new pressure tank proffesionaly installed about 2 years ago. I lost all water pressure for a short time no pressure in tank and after a while the punp kicked back on nut now it seems my water is running straight off the well pump and I have air in the pipes. What can I do?

On 2015-05-10 - by (mod) -

Brad

If your water storage tank is really 5000 gallons - that's quite large - it's possible that the pump is having such long on cycles that it's overheating OR that it is running out of water in the well ( a problem with low flow rate into the well).

Other problems could be a leak in well piping or a damaged pump that can't reach cut-off pressure. Some pressure switches include a feature that is intended to protect the pump from damage when it's run too long or may be overheating.

On 2015-05-10 by brad

have a 5000 gal. tank new 30/50 pressure sw. 85 gal. bladder tank 28 lb. charge pipes clean, but has to be manually actived. have no idea what the problem is/

On 2015-04-14 by Sam

Our toilets are hammering loudly when flushed, and the sinks (5) water pressures are good then weak and spit water at us (soaking my whole shirt)! We have well water and the tank was replaced 4 years ago. I tried to solve the problem by increasing the pressure to 60 (tank said it can go up to 100). No difference. Help!

On 2015-04-08 - by (mod) - normal water pressure tank life

Barbara,

With apologies for being very direct: BALONEY! A water pressure tank normally lasts for a decade or more, newer pressure tanks using an internal bladder even longer.

It would be unusual for you to need a new water tank so soon unless the one installed was defective, damaged by some external force, or improperly installed.

It is possible that the problems you are experiencing

- have nothing to do with the pressure tank:

for example a well running out of water or running low on water, possibly combined with a pump protection switch that might be installed - will turn off water to the building until the well recovers

- have to do with loss of the air charge in the pressure tank.

Call a different plumber and get some reasonable diagnosis of what's wrong before proceeding.

Keep us posted.

Daniel

On 2015-04-04 by Barbara Hendley

I had my water pressure tank 2 years ago because my water would cut off and on and I was told that is what I needed to do.

Now 2 years later I am having the same problem again and I called the company that installed the first one and told them I was experiencing the same problem and asked how long that tank was suppose to last. I was told by the secretary that it was only good for one year. T

hat is not what I was told when they installed it.

I was told that one should last me another 13 years like the first one. She said she would send someone to my home but would call me and let me know about the warrenty. No one called me back . The next day they just showed up and knocked on my door and told me my bladder in the tank had busted again because something had got into my well.

I don't know about these things and I could not understand what he meant by something had got into my well which has a submersible pump.

Said he would have to go get another tank. They came back and installed the other tank. 3 days later I get a big bill in the amount of $447.00. I call them back and asked to speak to the manager. The manager is not in and I am getting more excuses from the secretary of what caused my problem and the reason for this bill. She is just a secretary and does not know anything about plumbing and i asked to speak to the manager.

She said again she would have to get back to me on that. I was told that one time to many and I insisted on speaking to the manager. She said she would have him call me back. I waited all day and got no call.

The next day I get a call from the secretary again and she left a message on my answering machine that she had spoken to Larry( manager) and he said to tell me that the warranty on the tank was only good for one year. Now I am being told the reason the bladder busted so quick was because there is mud in my well and not because the tank was bad. I want to know if this is true?

On 2015-01-11 - by (mod) - air pressure creeping up in the air compartment of an internal-bladder water tank

Yes, though there is an obscure problem we've discussed in this article series: air pressure creeping up in the air compartment of an internal-bladder water tank. This might happen if the bladder has a small leak that sends water one-way into the air chamber.

Eventually if enough water is in the air chamber the tank operates as if it's water-logged and water might even be found at the air valve. But well before that we might see higher pressure.

On 2015-01-11 by Neil

should the pressure gauge read about the same as the air pressure when I take a reading at the top of the tank

On 2014-12-10 - by (mod) - When the pump can't get water pressure over 38 psi

Mike

When the pump can't get water pressure over 38 psi I suspect a well low on water, a leak in well piping, a damaged pump impeller, low voltage, mis-wiring, or something else to be figured out. Maybe the artesian well is no longer artesian. Or maybe a new pump is higher horsepower and exceeds the well flow rate.

The tank pre-charge is normally set 2 psi below the pressure switch cut-in pressure.

On 2014-12-09 by Mike H, Toronto

I installed a completely new system to replace my old 1/2 HP and 10 Gal tank. The new pump is a RedJacket 1/2 HP wired 230V and the tank is a 20 Gal. The tank came charged at 38 PSI, so I dropped it down to 28 PSI to match the 30/50 setting on the pressure switch.

The first day, it ran no problem as per the settings. Now, a day later, it won't build pressure past 36 PSI.

The old setup was inherited when we bought the place, and it had been adjusted from factory settings.

The pressure gauge was inaccurate, so it's tough to know what the old system was set up for.

Is it a situation of dropping the pressure switch down to 25/35 or 20/40 and adjusting the pressure in the tank, or is there some other solution I should look at? There are no leaks in any of the plumbing, no obstructions, and the well is artesian and has adequate flow.

I have about 10 PSI of flow without the pump on, just because of natural pressure from the well.

...

Continue reading at WATER TANK AIR PRESSURE ADJUSTMENT - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER TANK AIR PRESSURE SETTING FAQs-2 more questions & answers about how to adjust the air pressure in a water pressure tank

Or see these

Recommended Articles

• NO WATER PRESSURE if you have no water at all.
• WATER TANK AIR, HOW TO ADD
• WATER TANK AIR HOW MUCH TO ADD
• WATER TANK AIR PRESSURE ADJUSTMENT
• WATER TANK AIR VALVE REPAIRS
• WATER TANK BLADDERS & CAPTIVE AIR

Suggested citation for this web page

WATER TANK AIR PRESSURE ADJUSTMENT FAQs 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

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---