I have a pretty standard setup at my house for a home that is on well water. There is a pressure tank that gets filled by the well when the pressure in the system drops below some pressure limit (40 psi in my case) and it turns off once the pressure reaches the upper limit (60 psi in my case). The pressure tank provides for more uniform water pressure and since it stores a fair amount of water (40 gallons or so), it reduces the number of times that the well pump needs to turn on and helps prolong the life of the well. This is a vital function to prolonging the life of a well pump since if a well pump gets used too often it can overheat and fail. This is a very expensive repair, so it is to be avoided.

Recently I had an issue where my well was doing what is referred to as short cycling. The pump was turning on every five minutes, even when no water was being used in the house. Once the pump turned off, you could watch the pressure gauge on the pressure tank and watch it slowly drop until the well pump turned on again and increased the pressure again. This is very bad since this type of continual use will lead to overtaxing the pump in the well and it will lead to pump failure.

If this happens to you, it's an indication that you have a leak somewhere in your system. In my system, I had a shutoff for my outputs from the pressure tank. I turned these off and the behavior continued with the well repeatedly turning on. Unfortunately I did no have a shut off valve from the well into the pressure tank (an oversight when this was installed), so I couldn't confirm that the leak was between the well head and the pressure tank, but it was a good bet that this was the case.

From what I am told, the most common place to get a leak in a well system is between the well head and the house since that section of pipe is buried outside and subject to the elements. If you have a leak out there, it's not necessarily the case that you need to dig up the pipes (very expensive unless you have your own digger). What I did was to install a check valve where the supply pipe comes into the house. A check valve is a one-way valve. In this case it allows water to flow into the house, but it does not allow water to flow back out. When you get a leak in the line like I head, the problem is that the pressure in the pressure tank is pushing water at 60 psi all the way back to the well head. If there is any sort of small leak in the line, water will be forced out by this pressure. By installing a check valve (I also installed a shut off valve since there wasn't one there already), this keeps the pressure in the pressure tank from pushing water out through the leak in the supply line. In my case, this completely fixed the problem. Considering that this could have cost thousands of dollars to repair, the $20 for the check valve seems like quite a bargain.