tank drains when pump shuts off

Here is our problem. We have a shallow well pump that fills our pressure tank. Last night I noticed when the pump shut off, I heard running water and then the pump kicked back on. After making sure there were no open faucets or visible burst pipes, I unplugged the pump til I could look at it in the light of day. This is what I found: The pump fills the tank, shuts off and the water in the tank flows back out. I personally think that the back flow valve has somehow malfunctioned, but I've gotten all sorts of advice (non-plumbers) Any ideas?

Are you sure you don't have a leak somewhere on the house side of the pressure tank? Leaky toilet maybe? I would leave the pump plugged in and close the shutoff valve to the house and see if the pump still cycles or not.

Or it could be a bad check valve or foot valve or a leak in the pipe in the well, all of which are harder to fix than a leaky toilet.

-rick

That water is going somewhere , either a leak between the pressure tank & faucets or going back down the pipe toward the well . I would think if it was on the well side the pump would lose its prime . Is there a shutoff valve between the pressure tank & the house plumbing ?

Sorry was posting at the same time as previous poster.

drick said:

Are you sure you don't have a leak somewhere on the house side of the pressure tank? Leaky toilet maybe? I would leave the pump plugged in and close the shutoff valve to the house and see if the pump still cycles or not.

Or it could be a bad check valve or foot valve or a leak in the pipe in the well, all of which are harder to fix than a leaky toilet.

-rick

Click to expand...

Sure check that, but that would take a long time to drain the tank. My guess is the check valve (or foot valve depending on the configuration).

tank configuration

Okay, here is my tank configuration. Unfortunately, it may be a little long. We originally had a ram pump that pushed the water from our spring head to a holding tank up above us, and gravity would bring the water down to the house. The pump had been in operation since 1928, and unfortunately the cost to replace it outweighed the cost to install a pump and pressure tank. The plumber tapped straight into the original water line between the spring head and the ram pump. I have crawled under the house and have found no leaks. Now, when the pump shuts off and the water leaves the tank, it flows back through and out the vent pipe that is in the middle of the yard (required on a ram pump configuration). There is a shut off valve between the tank and the house, and I'll shut that off and see what happens. Now, not being a plumber, and only having a basic understanding of plumbing, isn't the check valve supposed to keep water from running backwards?

I guess the one thing I should have mentioned in all this is that it is a spring head and not and actual well. I checked the spring and it is full. I also turned off the water between the pressure tank and the house and the water still runs out of the tank.

Looks like your first guess seems to be correct. I'd replace the check valve at this point.