I have a shallow well (about 20ft) for my sprinkler system. Pump is in the garage connected to the well by one pipe. Neighbor replaced a valve he said was to prevet the water from flowing back into the well and keep the prime. The valve is horizontal about 20 ft from the pump. If I prime the pump it works fine, plenty of pressure and will run for hours. It will keep the prime for about a day, after that I have to re-prime. There is no tank on the system. Seems like everyone in the neighborhood has the same setup. Any suggestions would be appriciated.