Pump won't hold pressure when running water.

Okay so my 1hp pump will build pressure to 50psi no problem shuts off fine and the water squirts out all nice and wet. The pump will start again at 30psi like its suppose to, but here's the rub, once the pressure gets to around 30psi the pressure suddenly drops and the pressure gauge just wiggles from around 5psi to maybe 15 or 20psi and maintains that craziness until we shut the water off and then the pump builds back up to 50 nice and neat. It doesn't appear to matter whether the pump is running or not. If I turn off the power to the pump and turn on the water, everything is great till about 30psi then it just suddenly drops. The same thing happens if i let the pressure drop normally to about 40psi then force the pressure switch to start the pump. It slowly loses pressure to 30psi then drops. At no point does the water stop and air spurts out. We don't appear to be running out of water. There are no leaks at the pump or the tank and the tank is brand new. We have a stop valve by the tank to element any leaks on the supply line. I dunno about the pipe going into the well because its all underground. I guess the next step for me would be to pull that sucker out, but even then I really wouldn't know what to look for. Any ideas would be greatly appreciated! I've had to replace every single component on this well setup. The pump, the tank, the pressure switch, leaks, even the pressure gauge was bad! yay!

Thanks!

Nathan

You are running a greater volume of water than the pump can supply. This could be caused by a bad pump or a restriction in the line. A sticking check valve could be the restriction. I would tend to believe that a leak would eventually introduce air into the system.

I would start diagnosis by measuring the GPM of water that the pump is supplying from the well.

Well we haven't replaced the check valve yet. Is there a way to check if its bad? Thanks for the quick reply!

Do you know if you have a screened well or not? If it is screened, the screen can be plugging up and causing the pump not to keep with demand. Many years ago there were lots of drillers changing screens in small wells. Today, most of them just want to drill you a new/bigger one.

You need to do some research on your well. Find out the size of the casing and if it's screened or not.

bob...

Oookay, it is a screened well and apparently a month or 2 ago bleach was poured in there to clean out the screen. The casing, if you mean the pipe that the venturi? tube goes into, then we think its 2" and the pipe inside is 1". Unfortunately this isn't in my backyard and I can only get to the well once a week to work on it. I"m told the check valve is new and the foot valve is new. Apparently this is the same problem we had with the old pump as well. Though they are both used pumps. The pump was sitting on top of the tank but was lowered closer to the ground when the new "used" pump was put in. Everything appears to work, it just won't hold pressure with water running. It suddenly drops to very low pressure when it gets around 30psi. But always pumping out water. I unfortunately cannot afford to dig a new well. I do own a shovel though!

Thanks Bob!

New footvalve, jet and droppipe if that's the case is great, but if the screen is plugged (which it sounds like it is) it will keep getting worse, until you have no water at all. I can't say how long that will take because it is extremely variable from well to well.

This is not something you can do without the proper equipment and a lot of knowledge. Changing a screen can sometimes be harder than drilling the well. It definitely requires more skill and knowledge.

The reason the pressure drops from 30 drastically is because that is the precharge in your bladder tank. Once it hits the precharge, the tank no longer has any water in it.

bob...

Ah crap, that makes sense. So I probably need thousands of dollars at this point. Doh! I guess I'll call around for estimates. I really appreciate your help Bob. Thanks!

When I left Michigan in 1982 we were changing a screen in a 2" well for $450.00 plus the screen and check valve and any other needed items. That figure has probably excilated a bit in the last 25+ years. That's if you can even find anyone who does it anymore.

Good luck,

bob...