In a lift station with three pumps, where pump #1 check valve is stuck open, which condition is most likely the cause?

• A. pump # 1 & #2 are air bound
• B. pump #1 check valve stuck open
• C. either pump #1 or #2 is wired backwards
• D. check valve on pump #3 is clogged

Answer: (B)

In a lift station, each pump typically has a discharge check valve to prevent backflow from the discharge line into the wet well when the pump isn’t running. If the check valve on pump #1 is stuck open, backflow can occur into the wet well, so the discharge line cannot be isolated. This backflow directly explains the observed condition because it compromises the pump’s ability to create net head and can cause abnormal wet-well behavior or pump cycling, which is the most direct consequence of a valve that won’t close.

The other possibilities don’t fit as neatly: air binding would involve the suction side and priming issues rather than backflow in the discharge line; wiring backwards would produce incorrect motor rotation or startup behavior rather than a leakage back into the wet well; a clogged check valve on pump #3 would affect that pump specifically, not pump #1.