I live in the country. Our water supply is our well. The submersible pump cuts in at about 37 psi and cuts out at about 54 psi. I have noticed the sound of the pressure switch turning on the pump when there is no water being used. I watched the gauge at the pressure tank and I lose about 8 to 10 pounds within half an hour or so. I have checked everything I can think of for leaks including the two outside faucets. There is a very slow leak from a shutoff valve under one of the bathroom sinks but that leak is maybe half a cup in over a week and I don't see how it could be causing the pressure drop I am experiencing. If I close the valve at the outlet of the pressure tank for a minute or two and then open it there is the sound of water surging through the pipe to "fill the void" caused by mystery leak. Could a leak in the line from my pump to the pressure tank in my basement cause this type of problem? Any advice greatly appreciated!