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Could that be the winterizing hose that sucks pink into the pump to distribute around the camper. Mine has an intake very close to the pump and has its own diverting valve.
Have you check your owners manual under "winterize"?
2017 SLX 195RB
2014 Jeep Grand Cherokee Overland, gas 3.7 V6
Andersen WDH hitch
Dometic Milenco Aero mirrors