water line problem

Basic RV water system.....
City water and pump discharge are SAME.
They both feed the cold water system which then has a line that goes into water heater which then feeds the hot water system.

Check valves are part of water system.
One at city water connection so when using pump water doesn't flow out city water.
One inside pump so when using city water connection water doesn't flow backwards thru pump and overfill fresh water tank


If you have water coming out of top of pump......
Pump housing is cracked
Pump discharge hose/fitting is loose/cracked

Do you have a city water/ tank switch (valve) if your wet bay. If its on city water it should bypass the pump unless the line cracked or pump filter cracked from over tightening from cleaning filter.

Yes we have a pressure reducer attached.

A pressure regulator (what wolfe10 calls a pressure reducer) is sometimes needed, as some camp "city water" supplies are at pressures too high for RV plumbing. I don't know about your rig, but the owner's manual for mine recommended one and specified that the plumbing was only to be pressurized to 60 PSI. I was at a campground once where the city from which they got their water insisted on supplying it at 150 PSI. If you hooked up to that guy's water system without one, I'd anticipate something like the water pump cracking and leaking, if not somewhere else simply blowing out.

Water pressure regulator is like an electric surge suppressor: you might get away without it for years. You also might have bad things happen the first time out.

First question: do you have a pressure reducer on the city water supply?

Disconnect the outlet line and install a 1/2 inch plug is the easiest way to remove pump from system. Most pumps have a 1/2 pipe thread connection. Verify yours is that way.

Yes, normally the water goes towards the pump and an internal check valve keeps the water from going through the pump and into the tank.
It sounds like either a seal has failed in the pump or somewhere along the line it froze and the housing cracked.
I would take the pump apart and check it out. It may be very obvious what's wrong.