Keystone Bullet No-Fuss-Flush

[Rudney]

I have a Keystone bullet that has a black tank flush capability. After draining our holding tanks after our first trip this year, I connected the hose to the flush outlet, turned on the water, and until I saw water coming from under the trailer did not realize the water was not making it to the tank. When I looked in the trailer there was water all over the floor. The sewer valves were open. There is obviously a leak of some sort, and all the lines seem to be under the sink. I have not looked at this in-depth yet as we just cleaned up the water and parked the trailer, but I was looking for any insights before I head out again to trouble shoot the problem.

[cw3jason]

Your vacuum breaker or what some people call a anti syphon valve or check valve did not seat properly when water was applied to open it causing a leak. This is fairly common. I'm guessing yours is located under the sink. Remove it and inspect it for cracks. Test outside the camper and see if it will seat properly. Some have replaced with a brass model, others have removed it all together. It has a purpose and that is to prevent a back flow of black water. If you are going to get rid of it, consider installing a check valve in its place to prevent the back flow.

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[Festus2]

Somewhere in your RV, under the bathroom sink, or behind a panel, there is a vacuum breaker check valve. Numerous members have experienced much the same as you just have - water all over the floor and coming out of the underbelly. This is because this valve has cracked, broken or separated from the connection leading into the black tank.

It's just a cheap piece of plastic and hasn't stood up to the pressure of the water in the line or wasn't hooked up properly.

This plastic valve needs to be replaced with a metal one (brass) and they can be obtained at most big box stores - Lowe's, HD, etc.

The valve and rest of the nearby plumbing may be located under the bathroom sink as I mentioned earlier. If not, it is usually in a direct line with the exterior fill hose inlet and "hidden" behind a partition or panel. There are no directions with your unit as to its location.

Do a forum search and type in "black tank check valve" or "black tank flush" and you'll find plenty of info about this topic and what others have done to remove and replace the valve with a proper one.

[CFDfireman90]

I hve a new Bullet as well. Under the bathroom sink you will see white pex water lines, they are for the black tank flush. They go way up to the under side of the counter top. There is a check valve/vacuum breaker/one way valve, whatever you choose to call it, in line there. Several possibilities exist, the check valves go bad, even brand new ones. But for starters make sure the connections are intact and tight. If they are the valve is probably bad. Having read this same horror story on the forums so many time I have removed my check valve and just attached the 2 threaded ends of that line with a plastic threaded close nipple. I bought a check valve to put on the garden hose when I use the black tank flush. And to beat everyone else to the punch "never use you fresh water hose for flushing you black tank.

[Rudney]

Thanks for all the advice!

[therink]

Fyi, I see you live in the Great White North. If the flush system was used last season and not winterized (water blown out of it) the valve can freeze and crack if all water is not removed when winterizing the rest of the plumbing.
I hope you locate the valve.