A "What Is It Question"

[RKassl]

Under the vanity in our 2015 3440RL 4 water lines come up from the basement. I can tell the hot and cold, they are red and blue. No problem. But there are two white lines that seem connected by some sort of black thingy. What are these for and what is that black thingy that connects them together?

Thanks

[mjammersc]

That is the line for the Black Tank Flush and the black thingy is a backflush preventer valve (one way valve).

[RKassl]

Thanks, from what I have read around here I thought that what it could be, nice to know for sure. Haven't some folks had problems with the one way valve and had to replace it?

[Good Life]

Any pics?

[mlh]

A lot of people have trouble with it. Most people me take it out and throw it in the trash can or replace it with a one way valve. That is what I did.
Lynwood

[beeje]

I got rid of mine as soon as I read about trouble with them leaking and flooding out campers. That was not going to happen to me. I cut the line going to, and coming from it and connected them together with a 90. Potential problem solved before it became one.

[prndl]

If you remove the back flow device and connect the lines together you will have the potential to have a siphon and then have black water come out of the hose connection in the utility center.

The only time this device could flood the trailer is if it broke while you were flushing the tank. It is not otherwise pressurized. However, flush valves on the toilet can fail and overfill the bowl and the rig.

Turn the water supply off when you're not home.

[DQDick]

I cut out the one in the old rig and will get the one in the new rig this winter. I replace them by using a metal backflow preventor on the outside connection. That way I still won't get backflow into the hose, but I've got that POS out of the rig.

[beeje]

prndl, I don't see that ever happening. I have been all over my camper from top to bottom. I know exactly how everything is plumbed and wired. I have had the entire coroplast enclosure off to straighten everything out in the underbelly. What a mess it was. The black tank flush is mounted up near the top in the back of the black tank and goes up hill quite a bit to the convenience center. My tank never gets full enough to even have that nozzle submerged. I never travel with anything in the holding tanks. I have been to campgrounds that are very rough and have gone down steep grades to the dump station with that tank 1/2 to 3/4 full and have never had a drop come out of the hose connection. As for using the sprayer to clean the tank, there is no way for the water to go backwards since the tank would be near empty when in use and that sprayer nozzle in the tank would be know where near the fluid level. Even if one did have the issue you described, it could be fixed in seconds by installing a in line CTS backflow preventer.

[BB_TX]

Like some others, I removed mine and use an external backflow preventor valve. Was doing a flush when DW began yelling that water was coming out of the pocket door and running across the floor and down the steps. My valve was in the wall behind the shower and behind the pocket door. Valve pipe fitting had broken off. And yes, it did flood the floor before I could get it shut off.