BoilerMan
Minister of Fire
Exactly what I'm talking about! When I install submersible pumps, I put a secondary check valve on the pitless, just before the 90 degree turn out of the casing. No other check valves should be installed inside the house. This way there is always pressure on the pitless' Oring which will make it last the life of the pump (typ 20 years).
TS
TS