Losing pressure over time

Hello all, My Deep well jet pump (well is approx. 80' deep) pump has 30-50 switch, and pressure tank is set at 28psi, and although old, is not leaking air or water. Problem started a couple of weeks ago where I would lose pressure over about 20 minutes, thus making the pump kick back on and recharge to 50psi. I shut the valve to the house off , and still had problem. I pulled the well, replaced the foot valve, all fittings, as well as the ejector assembly since I was going through all the trouble, put it all back together and primed the system All was working well, except same problem was still there. Now it is getting much worse and I lose the pressure in about 4 minutes. I assume I must have a leak somewhere in the lines, and am waiting for warmer weather in 3 days to pull it. Funny thing I noticed though, if I shut the pump off, overnight and close the house valve I have to re-prime it to get it going. If I shut the pump off, and close the valve between the pump and the pressure tank, I don't have to re-prime as the water is still in the lines and pump and doesn't appear to leak out? Is it possible for it to only leak with some pressure on it, or am I missing something here? the order of my system is (well, pump, shutoff valve, pressure tank, and shutoff valve to the house.) Thanks.......

Without back pressure, whatever is leaking under pressure, doesn't leak. Meaning it isn't all that big yet but will likely get larger with time.

The leak could be underground instead of in the well. Or if you have one, it could be the pitless adapter oring.

How old is the well?

bob...

The well is about 41 years old. Not sure if the lines are all original or not.

Thanks Gary, That's all I could figure, I will have to just pull the well again, and maybe plug and pressurize the lines to see where the leak is!

I believe you said this is a deep well system with a jet down the well. If so, you won't find the leak. Chances are it's the casing which is used as the back pressure line. The surface water at the 10 to 20 foot level in most cases has a PH of around 5. This water can over a period of years eat holes into the casing. If this is the case, the pump would have started out by coming on occasionally for no good reason. This condition would worsen until it gets where the pump can't make shut off pressure anymore. Then the pressure would keep going down slowly until the pump throws it's prime. At this point there is nothing you can do if it's a two inch well. If it's a three inch you can install a Submersible Pump.

bob...

Thanks Speedbump, I have a 6: casing/well, and the jet pump has two lines going into the well, the 1" pressure line, and the 1 1/2 suction line.

That could have saved me a bunch of typing had I known.

Now I would definitely go for the submersible pump. Performance and dependability go way up with one.

bob...

Thanks, I have been seriously thinking about putting in a submersible, with all new line etc., and be done with this problem. I just have to test the underground (well to house) line to make sure it is not leaking since I would rather avoid digging right now.

You can't get away from the digging if installing a sub. You will have to install a wire to the well to run the pump. Unless the old pump is already at the well and the wire is adequate to operate the submersible pump.

bob...

Losing pressure

Yep! 6" casing. . . install a 4" 1/2 hp submersible pump and be done with it. Submersibles are like refrigerators. . . they either work or they don't. If they don't, replace them.