I've lived in this house for a little over a year now. We have a well, well pump, and using the challenger series diaphragm well tank. Tonight is the first night that I've noticed a sound the keeps coming on and then shutting off at the tank. I felt the hose coming from the tank going into the house and it felt like water running through it. I checked the house and there was nothing on or washer running. I noticed the gauge on the same line; I take it is a pressure gauge and it keeps moving up and down from two to four each time the sound comes on. As you can see I'm not very familiar with this, but I know it's not normal.

Do you have a filter? Filters backwash every two days or so. Could be that.

Not sure what you mean by "it keeps moving up and down from two to four each time the sound comes on." Surely you are not down to only four pounds of pressure.

Another possibility is a leaking checkvalve. The CV is meant to keep water from running back down into the well every time the pump turns off. It's a one way gate. If it is defective, then when the pump cuts off, the water in the tank will simply run back into the well until pressure drops enough to cut the pump back on.

Do you have a shut off valve going to the house? If so, then shut that and see if the problem continues. If it does, the either a CV or a leaking wellpipe is your problem.

Thank you. It was late last night when this problem started. I read the pressure gauge wrong. The system would turn on every 5 minutes. When the PSI got to 62-64 it would turn on again till it dropped to 44 PSI.

I am assuming you are saying that this happens when no water is being used. If that is the case, and again assuming that you have no leaks, then it sounds like a leaking/defective checkvalve. If that is the case, then you can install a checkvalve between the wellhead and the pressure tank. Not hard to do. Check out the link below.

Water System Backflow Preventers & Check Valves - DIY repairs

Just to be on the careful side, you should check your tank to be sure it is not waterlogged. There is a little air valve at the top. Press the stem for a few seconds. You should get nothing but air. Water would not be good.