For those just entering the rv lifestyle there is a check valve behind your city water hook up.
Rv check valve leaking.
Use good rv anti freeze when winterizing your rv.
I had a plumber at home depot tell me you could not use pex clamps on a plastic fitting yet my rv service manager says the rv industry has been doing just that for 20 years.
The valve is designed to let pressured city water enter the rv s plumbing system when hooked to a charged hose bib via your water hose in an rv park and prevent the water pump from pumping water out of your potable water tank onto the ground when not hooked to a charged hose bib.
It s hardly an owner friendly arrangement but i have seen it.
If nothing poured out repeat the above steps for.
Our city water connection has been weeping water when using the onboard water pump and fresh water tank for dry camping.
With the wastewater valves closed and the black cap off place a 5 gallon bucket under the sewer drain port.
Check amazon or rv water filter store for options.
Inside is a plastic check valve plunger a spring retaining clip and small rubber o ring.
To determine which valve is leaking you should have your rv waste tanks empty.
Dislodged check valve seal under the mesh screen in your city water inlet there is a little valve that is meant to prevent backflow when using your water pump.
This will help keep the dump valves from becoming sticky after they have sat for a long time.
Add your own 1 way check valve to the water line on the inlet side of the pump.
Did any water leak out.
If you do not want to fool with broken or stuck dump valves.
Go whole hog and replace the pump itself.
Wait about 30 minutes then head outside and slowly uncap the waste pipe.
I figured what was happening is the check valve was leaking due to a dislodged worn or damaged o ring.
Many moons ago the owner of the site called me on a sunday evening to help me.
I bought a 3 years old 5th wheel and found several leaks in the plumbing behind the dividing wall in the basement.
A small amount of leakage is normal but anything more than a cup and you ve got a leaky gate valve.
The leaking issue may be coming from a cracked pipe or a loose connection.
It is a messy job but someone has to do it.
An occasional rv will be found that has a 3rd dump valve and even 2 separate dump hookups.
If you don t know what you need rv water filter store s customer service is fantastic.