Hi . My pump was 20 years old and had worked fine for that time . Thinking perventive maintainace , I had the pump changed . When this was done , the well repair man removed the 5 gpm flow restricter { dole flow valve } . Three months later , the new pump quit and the well was full of very fine sand , and I was told by him that I needed a new well . The well has been baled out , the restricter valve replaced , and for now it seems to be OK . My question is does this valve help keep sand from coming through the screen or is the screen not working properly . PS well is 440 ft deep .