Bullet Black Tank Spray Failure

[RV802]

I have a 2014 Bullet Premier. Until this week, after draining the black tank, I have always hooked the dump station hose to the connector on the back of the trailer and given it a healthy dose of water to free up any waste that may be loitering in the tank.

This week when I tried to use the sprayer it was evident that no water was going into the tank. I closed the dump station faucet and when I disconnected the hose there was considerable pressure at the connection and water sprayed out as I loosened the connection.

We then discovered that water had come out of what looks like a vent valve under the bathroom sink.

I also realized for the first time that the outside connection doesn’t lead director to the black tank but, instead, connects to the plumbing system and eventually gets to the tank by a path I can’t readily follow.

I’ll try to attach a photo of the lines under the sink. The lower red arrow is where the pipe comes in from the rear of the trailer, the upper arrow is the device that leaked.

Any ideas as to what might be going on?

Thanks.

[JimQ]

That fitting is a plastic, very cheap backflow preventer (anti siphon). It's crap. I took mine out and put a shark bite 90 degree elbow and use a backflow preventer on the hose connection outside, you can purchase one at any hardware store. Good luck. Very common problem.

[JRTJH]

You've got a broken/malfunctioning anti-siphon valve. It's the component in your photo at the top arrow.

The black tank flush system is not "connected to the plumbing system. It's a separate line that goes from the connection on the side of your trailer, to that anti-siphon valve, then down to the spray nozzle in the tank. It doesn't interface with any of the fresh water plumbing (other than sitting beside it under the vanity).

You can replace the valve with a similar one (available at any RV parts store, EBay or Amazon) or upgrade to a more reliable anti-siphon valve. They are available at Lowe's or Home Depot in the irrigation section. You'll need to also buy fittings to attach that valve to your current fittings where the old valve was removed.
Here's a photo of a typical black tank flush system.

[RV802]

Thanks much! Seems like a doable fix. Didn’t really think the spray line intermingled with the fresh water, just couldn’t see where it went after it left the vanity area. Happy trails and thanks again!

[Roscommon48]

to me it is a waste to 'flush' the black water with the hose. Just get the tank nearly full of waste and water and dump. that's it. learn when to dump, probably every two weeks if full timing.



never used the back flush on our unit and never will. you don't need a 'clean' tank like some people try to do...it is a black water tank.

[JRTJH]

to me it is a waste to 'flush' the black water with the hose. Just get the tank nearly full of waste and water and dump. that's it. learn when to dump, probably every two weeks if full timing.



never used the back flush on our unit and never will. you don't need a 'clean' tank like some people try to do...it is a black water tank.

To a certain point I agree. If the tank is "being used" it's pretty much "pointless" to try to clean it to make it dirty again... The only time I try to get the tank "relatively clean" by using the black tank flush, is when I'm getting it ready for winter storage. Otherwise, I pull the plug, let it empty, close the plug and start filling it again. To me, trying to 'clean the black tank is much the same as trying to scrub the pit walls in an outhouse.

[sourdough]

I use the blank tank flush all the time when we have the ability to do so. I understand "filling it up", dumping and filling again. The problem is that there are always residual "things" left in the tank when just pulling the handle and dumping...they don't come out (just run the black tank flush after every dump...there it is). Repeatedly doing this for the long term will cause problems IMO. Plus, running the flush takes all of 5 minutes. Sort of like "err on the side of caution" and there's nothing to it.

In the old days there was no such thing and never did it. Nowadays it's there, it's easy and just another way to make sure you don't have just one more issue with the RV. JMO/YMMV I'm sure.

[Logan X]

I use the black tank flush maybe once or twice a year just to get out the residual mess that gets stuck in there. It’s easy enough to do.

[RV802]

Dan, my approach exactly. Many dump stations have broken hoses or damaged fittings. I do it when I can...and if there’s no line at the station. Black tank level indicators are unreliable at best, but I find that mine do tend to work better the times I have back-sprayed.