The foot valve may be starting to stick open in my mother's well system. It is a 2-line jet pump deep well system. I started looking online to see if anyone had ever added a check valve near the pump as at least a temporary fix, but I could only find check valves discussed for shallow well systems. However, today I was talking to a friend and he said he actually did it for the same problem and it worked. He's very handy and had built his own home. In my mom's case the well is located somewhere underneath a 4 ft high deck, and since it's winter it's even more inconvenient/difficult to dig things up. Anyone done it successfully? I did see that on the shallow well systems they say to keep the check valve at least 2 ft from the pump, and we don't have that much room. How much of a deal breaker would that be? Thanks for your help.