The Tapering Pressure Pump Mystery

Help. I have been battling with this situation for almost a half year.

I installed a new 3/4 hp, 2 wire, 230v deep well pump last December. The unit had some issues with low flow at first but after turning it off and on a few times I had no problems.

About 6 months ago I shocked my well with H2O2 and shortly thereafter I started having pressure problems. The pump would violently start, almost seems like water hammer, and then just hum along. I would get a burst of water pressure up to 30 psi and then it would just taper off quickly to below 10 psi. Flow is just a trickle. If I keep everything off in the house it gradually builds to 60 psi. Pump turns on back again at 40 psi but same problem.

I even replaced the pump and put new wire and a new breaker in the box.
Same thing.
Specs: Well is 160 feet deep, Pump is at 140 feet deep. Water level is 2 foot from top of casing now. One check valve is in place at 40 foot down (could it be the check valve? I replaced this just 2 years ago). Torque arrestor is in place. Pressure tank has new bladder with pressure at 38psi.
Continuity shows from each leg of pumpwire to ground. But I am getting continuity from leg to leg.
Voltage is 115v on each leg to ground.

Is this electrical? Is this the check valve?

Dump the check valve, there is one on the pump.

Peter and Guys,

Thanks. I removed the check valve and the unit is performing flawlessly. I wish I had found this forum 6 months ago. It would have saved me a few hundred dollars and immeasurable grief in pulling this pump about three times.

I'm going to full pressure in seconds now and have seemingly unlimited flow.

I am a licensed engineer and would have thought that there was no way a brand new check valve would have created this problem, but sure enough.....


Bill Gillette PE

Happy to have been of service.