water pump location and replacement

Don't know your specific model, but they are usually in a cabinet or storage area (like under the dinette) at floor level. They are always left accessible so it's not like it's behind some secret panel. Under the kitchen sink is a common mounting place. *Generally* they won't be located in slide-outs or in the upper level of a 5er.

Or call call Jayco Customer Service at 800-283-8267 with your model # and serial #.

As an aside, how do you winterize the unit if you don't know where the water pump is?