If the leak is where that arrow is someone did not put that glue joint together right, or more likely used the wrong kind of PVC glue, those black pump fittings are CPVC and the pipe is PVC so you have to use the special "universal" CPVC / PVC glue (usually comes in a red label can), not the more common PVC to PVC (blue, green, black, etc. label) or CPVC to CPVP type glues (orange label).