Dear Dave,
I recently bought a used camper. I boondock, so have not hooked up to water in a campsite, only filling my onboard tank. On this trip, I did not fill the tank, but traveled with jugs of water. I washed my kitchen sink out with water from a jug. Later, when I walked outside, I noticed water leaking out of the connection to hook up a water hose. How is that possible? I must be missing something. Thanks. —Brenda, 1998 Casita, Spirit Deluxe, 17 ft.
Dear Brenda,
Washing out the kitchen sink with your jug of water should not get anywhere near the city water connection. The water would go down the drain, through the “P” trap, and into either the black or gray water tank. Your RV’s city water connection has a hose going directly to the fresh water tank. I believe you still have water in that tank.
Backflow valve in city water connection
The city water connection has a backflow valve incorporated into the center. It is designed to prevent water from the lines coming back out through it. It is spring-loaded with a small tip that should be visible. This valve is located behind the screen designed to filter calcium, lime, and grit from getting into the system.
When you activate the onboard water pump, it creates pressure in the lines and forces water through the cold line back to this connection. The valve is designed to stop it from running out.
Because the water supplied at campgrounds is typically well water and is not treated like a municipal system, you can still get some small grit that the screen will not filter. That could cause the backflow valve to stick open.
Also, when you fill the fresh water tank with hard water, it will come from the back side of this valve and clog it open. My guess is the onboard water pump is pushing water to this connection and the valve is not stopping it.
You can remove the filter and try cleaning the valve, or replace it with one from Amazon here.
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The poster said she was using jugs of water, not water from the tank, so the pump should not be running.
I bet she leaves her water pump on and she also says that she keeps water in her on-board tank. Pouring water down a drain isn’t going to come out the city water connection.
She should be able to hear the pump running periodically. However, she said she did not fill the tank for this trip. There may have bee enough water still in the tank though.
I still points to the check (anti-siphon) valve.
Does the Casita actually have a gray water tank? Some small campers don’t have a gray water tank, just a hose connection designed for using a bucket or blue boy tote.