If this is a submersible pump in a fairly shallow well and it is running continuously and only putting out 20psi, you have several possible problems:
The impeller assembly is coming apart and there is excessive internal leakage in the pump.
There is a leak in the pipe leading from the pump to the well-head, either the pipe has split, or the barb fitting nipple in the top of the pump has a hole corroded in it. The pump basically is recirculating the water back into the well.
Submersible pumps with iron pipe to the wellhead that use a below frostline casing fitting have an o-ring in the slider coupling assembly that can rot and cause a leak back into the well.
Not sure where the main water shutoff valves are. Are they in the pump house or at the residences? Any unexplained water bubbling out of the ground with quicksand like mud?
Note: A leaking foot valve will have one of two effects. On an above ground pump, you will lose prime, on a submersible, if there's air leakage, you get a slug of air into the system every time the pump starts (chugging faucets, etc).