# Surge in water pressure



## Robie (Feb 25, 2005)

My house has a well, pump and bladder-type tank. About 2 weeks ago, the system started behaving as follows:
If I run the water for the amount of time it takes for the pump to come on, the pressure drops dramatically just for a moment as the pump comes on. It immediately goes to almost zero pressure, then back up to normal. This all takes place in less than 2 seconds.
Any ideas of what causes this and the fix?
Thanks.


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## KillerToiletSpider (May 27, 2007)

Check the pressure in your tank.


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## Leo G (May 12, 2005)

Bad foot valve


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## piercekiltoff (May 28, 2009)

Bad check or foot valve could do it on a jet pump system. If it's a submersible pump, it's probably the bladder tank. Drain the tank, check the air pressure, and set at 2 PSI below the cut-in point of the pressure switch, then turn everything back on.


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## Robie (Feb 25, 2005)

Thanks. It's an above ground pump sitting directly next to the tank in the basement.


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## piercekiltoff (May 28, 2009)

Check the foot valve in the well - a lot of the time it's just a piece of sand in the check assembly in the foot valve.

Sounds like what is happening is that a check valve is installed right before the pressure tank (between the pump and tank), and it'll hold the pressure in the pressure tank. The pump comes down to the ON position and there is no water in the suction line (due to the faulty foot/check valve at the end of the suction line in the well) - so the pressure drops momentarily until the pump re-primes itself and feeds the house more water. Depending on how far it is to the water level, this may take no time at all, which is why you're seeing a momentary dip as opposed to a longer wait.


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## Robie (Feb 25, 2005)

Thanks for the help. I'm doing a little research and have come across an article that said most deep wells have a foot valve. My well is shallow. Is there probably a foot valve at the end anyway?


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## mics_54 (Oct 28, 2008)

> The pump comes down to the ON position and there is no water in the suction line (due to the faulty foot/check valve at the end of the suction line in the well)


How can this be in a closed system...the water in the suction line side of the pump would have to be replaced with air for it to drain out. 

My bet is a water logged pressure tank.


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## Robie (Feb 25, 2005)

I just ran a faucet in the basement. From the time the pump cycles on until it cycles off is 1 minute, 48 seconds. It shuts off at around 70 psi and comes on at 38 psi. It doesn't come on unless the water is running.


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## Leo G (May 12, 2005)

I would think any line that is down in the well would have a foot valve. What it is, is a check valve that prevents the water that has been drawn up the line from falling back out due to gravity. Once the water gets in the line it is trapped there. The only way it can flow it towards the pump. If somehow water is allowed to flow back down, every time you need the pump to supply new water it will have to reprime and fill the line back up.

So, as a general practice, I would think any well system would have a foot valve.


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## mics_54 (Oct 28, 2008)

How big is the PT?
How long does it take to drop from 70psi to 38psi? How many gallons?
I just replaced a PT last week that had a failed bladder. It only took about 1-2 gallons for pressure to drop to zero. The bladder was filled about half full of water.


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## piercekiltoff (May 28, 2009)

mics_54 said:


> How can this be in a closed system...the water in the suction line side of the pump would have to be replaced with air for it to drain out.
> 
> My bet is a water logged pressure tank.


Yes...it would, and it can - if the foot valve is out, the line never stays primed, so as soon as the pump shuts off, the water flows back down the well. 

What I was saying was that there are technically two check valve setups in most wells like this - one right before the tank (between the tank & the pump) and one right at the end of the suction line. The failure is in the well at the end of the suction line, which only is draining the pump suction line empty.

Technically, a closed system would be where he is pumping the water around in circles.

The tank is probably an 85 gallon tank, based on the cycle time, which is adequate for pump cooling. The tank is NOT the culprit, or his on-cycle would be much less.

For arguments sake - the only other way that the tank could be the problem is if it was water logged AND the pump wasn't yielding enough water to fill it at a decent rate - in that case he'd have a low pressure situation the entire time he had any faucet on, because the pump would turn on almost instantly, and not be able to deliver enough water to meet the demands being placed on the system, and then when the tap was turned off, it'd take the 1 minute & 48 seconds to refill the system. This means that with a water logged tank, the pump would only be producing roughly 1/10th of a gallon per minute. If the pump is that worn, it'll never create 70 PSI to shut the switch off.

Also, double check all air pressure readings with a tire gauge on the tank fill nipple - the air filled gauges that are common on well systems are pretty much junk.

There's a foot valve assembly on all shallow/deep well jet pump systems - in shallow well pumps it's really only a glorified screened check valve. The difference in the deep well versions is that there is an ejector nozzle built into the foot valve to allow the second line down from the jet pump to connect and create the double jet action. In shallow well systems, the ejector nozzle is built into the jet pump itself.

Just last week we replaced two pressure tanks, a jet pump, a submersible pump motor, drilled a new well, a water softener, rehabbed a well/cleaned the sand screens (well produced 6 GPM flow, now produces 12 GPM), and installed a 2000 gallon storage system with 50 GPM booster pumps. :whistling

Of course, now that I've said that, I reserve the right to say that I've never seen this particular system, so how can I properly diagnose the problems from thousands of miles away? Heh.


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## mics_54 (Oct 28, 2008)

so then tell me...how does air get into the suction line to replace the water that drains back into the well? Or does it just make a vacuum?


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## Leo G (May 12, 2005)

Both at first. Take a jug of water (soda bottle) and tip it upside down and the water will come out, then stop because of the vacuum. When the vacuum becomes a certain level it will suck in air and the water level will drop again. It will continue to do this until the water levels in the line and the well become equal.


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## mics_54 (Oct 28, 2008)

not if the only inlet is under the waterline like at the bottom of a well
...take the same jug....turn it upside down so the inlet is under water...no water will run out of the jug and no air can get in.


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## piercekiltoff (May 28, 2009)

Well, Mics is right on his last point, which means you've also got a leak in the suction line above the static water level.

I'd replace the whole system with a submersible pump, personally - jet pumps are a waste of time & space.


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## mics_54 (Oct 28, 2008)

jets are a reasonable solution to some applications like artesian wells where the artesian pressure isn't enough to satisfy requirements. PITA but downhole pumps in artesians are also.

Anyway...it would be interesting to know what the issue was with this one.


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## Robie (Feb 25, 2005)

Okay Gentlemen...again, thanks.
Here is some more info.
First, the pressure tank size is 13.9 gallon Goulds (pretty small, isn't it?)
I tried a digital pressure gage but it doesn't fit well, so I went with a quality tire pressure gage I keep in my truck.
The pressure at the tank is 34 lbs.
The gage on top of the pump comes on at 36 lbs and cuts off at 68 lbs. It takes 49 seconds for it to reach 60 lbs, but it takes another 60 seconds or so to get to 68 lbs...seems like a long, long time. Does the above info tell you anything?
I do appreciate the advice. I'd like to repair/replace what I can before calling in someone to tell me it's going to cost more money than I have to do a fix that maybe was unnecessary.


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## piercekiltoff (May 28, 2009)

Robie said:


> Okay Gentlemen...again, thanks.
> Here is some more info.
> First, the pressure tank size is 13.9 gallon Goulds (pretty small, isn't it?)
> I tried a digital pressure gage but it doesn't fit well, so I went with a quality tire pressure gage I keep in my truck.
> ...


Not jiving - is it 13.9 gallons draw down or 13.9 gallons total volume?

If it's total volume, you have a cycle stop valve or constant pressure valve that is controlling things, and which may be faulty.

When does the dip in pressure occur, when the switch turns on?

Shut the breaker off, drain all the water out of the tank, then set the bladder at 34 pounds, and then turn the breaker back on. See if that doesn't cure the problem.


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## Robie (Feb 25, 2005)

I compared the model number to a catalog on the net...13.9 total gallons.
Here's a pic. It's in a dark, dank corner of the basement, where my workshop is, so things are a little dusty.
The pressure drops almost immediately (just 1/2 second) before the pump comes on. As soon as the pump comes on, things are back to normal.


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## piercekiltoff (May 28, 2009)

Check the air pressure as I described in my last post.


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## Robie (Feb 25, 2005)

*Update*

Well, I ended up procrastinating with this until the water pressure would dip to zero and stay there for about 30 seconds.
Tackled the problem yesterday. The 1/4" copper tubing leading from the pump to the pressure switch was packed solid with mineral deposits. Changed out the switch, the gage and the tubing and all is well.
Thanks again.


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## piercekiltoff (May 28, 2009)

Don't see that too often, but that makes sense.

Thanks for the update, always good to know what actually ends up being the issue.


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