Well Pump - Low Pressure

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SunTzuMD

SunTzuMD

Joined
May 9, 2004
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Slowly developed a problem with low water pressure, on residential well.

Pressure never get's above 25 psi (used to get to 40 psi), pressure switch stays on and continues to run pump. When electrical shuts off, pressure eventually falls to 0 psi (1hr or less).

When I turn the valve off between the pressure tank and the rest of the house there is no change in pressure, so I don't think it's a leak on the house side.

Pressure switch seems to be operating correctly.

Bad pump or leak between pump and house?

Share . . . .
 
I've had that from the well pipe rubbing against the side of the casing to the point that a hole is formed. It holds enough pressure to supply water up to the house, but any pressure beyond that just spurts through the hole and back down the well.
 
Turned out to be a dead pump - replaced and now have 60psi in pressure!
 
Do you have any type of Pumptec type of controller to protect the pump? Also, Square D makes a pressure switch that shuts off pump if pumps output pressure falls below a threshold. You'll then have to manually reset the switch. FYI.
 
So we have a 3/4 HP 10 GPM pump with a cut out / cut in set at 60/40 PSI.

But we only have a 20 gallon expansion tank. All the online calculators call for a 37 gal tank. Big deal or not?
 
Casing is fine, no pumptec or similair device
 
Tank being too small could be the cause of your pump failure. It will make the pump cycle too often but the cycles will be very short, which is not good for the pump.
 
So I ran a couple of tests, starting with a full tank. It takes ~ 40 seconds to drain off 3.5 gallons from the slop sink next to the tank, before the pump turns on. I shut the water off at that point and then the pump ran for ~ 30 seconds before shutting back off.

I think I need a bigger tank as I understand that the pump needs at least 1min cycles . ???
 
I was taught long ago that fewer longer cycles is much better than many short ones. Might call a pump supply or water contractor, see if they have a recommended run time range, but seems like a minute is about the minimum to me.
 
I would think the bladder is bad in the pressure tank...I think that would cause constant on and off....make sure it's at recommended pressure and is holding.
 
That's a good idea, check to see if your tank is water logged. Drain the tank, then check the charge pressure on the schrader valve, should be ~40 psi.
 
You need to check the air pressure in the bladder with the tank empty of water, FYI.
 
Ruptured bladder was my first thought. I could see a small line leak will produce same results.

Ditto on the Pumptech motor controller. This will keep your pump from overworking when these problems develop. I have a 3 HP down 500 feet and I sure do not want to pull it out anymore than necesary.
 
Tank is working fine, it's just too small, I'm only getting about 3.5 gallons of draw down. By all calculations, I need a 35-50 gallon tank, not 20 to get adequate run times. Going to start remodel next month, will probably replace tank when I replace water heater then.
 
I still think you have a leak in your well or at the check valve at the pump if your losing pressure. I have a 10 gal per min 1 PH pump and was having problems getting to 60 PSI. The problem was a leak at the pump. There was a hole in the barb adapter at the pump so the water was just dumping back to the well and never going above 50 PSI.

Bad tank, small tank or ruptured bladder will make the pressure surge but not cause low pressure.
 
I think people may have missed the sequence of events: Low pressure, tank is working, pulled pump, there were no leaks in the pipe or check valve, replaced 15 year old pump and now we have fantastic pressure. Pump is cycling too often because tank is undersized.
 
Tank is working fine, it's just too small, I'm only getting about 3.5 gallons of draw down.
Click to expand...
from a 20gal tank? you mentioned that
Slowly developed a problem with low water pressure, on residential well
Click to expand...
how was it performing before?

Like the other guys say... isolate the tank and drain it. Then put 12 pounds air pressure into the schrader valve and see if it will hold the 12lbs for a few days.
 
Sounds like the pressure tank bladder to me also. Check the pressure by starting the pump and filling till it shuts off. Isolate the well pump discharge valve. Watch the pressure to see if it drops- if so, the tank bladder may be at fault. If not, open the well valve back up. If the pressure immediately begins to fall---check valve is bad.
How deep is the well? Do you have a submersible pump, or is it a surface well pump(or jet pump)? What is the water table?
Another thought after reading the post again-you said the if you isolate the house from the well equipment, the pressure stays up, but when the house valve is open it falls---that tells me you have a leak in the house piping.
 
Last edited:
The well pump died, we have replaced the pump since the start of the thread and have great pressure now. Just noticed that the tank is undersized per manufacturer recommendations of both the pump and tank manufacturers for our set up. The pump only cycles when we drawn down the tank, which is only giving about 3.5 gallon draw down from 60 to 40 psi. It holds pressure fine when none of the taps are on.
 
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