Confused about check valves

[Yi Ma]

I had a look at the following thread which is now closed: https://terrylove.com/forums/index.php?threads/submersible-pumps-and-multiple-check-valves.26301/

The diagram at the top says that there should be a check valve directly above the pump, but all most water pumps that are described here seem to have a check valve already included, so am I right to assume that no additional check value is required immediately above the submersible water pump?

 

[Valveman]

As long as the check valve that comes built into the submersible is a good one, that is the only one you need. If it is not a good one or you just want an extra, it should be installed a few inches above the pump.