Black tank flush system leaking

I have had the metal anti-siphon valves on all 3 of my Excels. Before I got a water softener early on, the valve would get mineral build up and the calcium bits would cause it to leak. Took apart and cleaned. Good to go. Lots of things that could cause this issue so just take a look and see which one it is. rockin'

Fittings could also be bad. But valve failures are also common. Here is a picture of the black tank flush anti-siphon/vacuum breaker valve from my Montana. And if you look closely you can see cracks running all thru the valve.

I am experiencing the same thing with my Outback. It started last summer. I quit using it after flooding the camper twice. This last week-end I had the wife turn the water on at the spigot and I watched inside. Mine is under the sink.

Turned out there is NOTHING wrong with with the anti-siphon valve.

The problem is right where the garden hose attaches to the outside. Water came gushing out all around there. As the outside is sealed completely with calking, the water had no where else to go but under the cabinet inside the camper.

I was going to disconnect it, but we were still camping, and if I remove the outside fitting (where the garden hose attaches), I want to make sure I have access for a replacement and a calking available. As we were camping when we ran the experiment, I decided to wait till we get home.

If you can run a similar test, I bet you will find the water hose connection is also spewing water inside the camper. Nothing is wrong with the anit-siphon valve. I was ready to take mine off too and just replace it. That would have been a waste of time and money. Check the connection where the garden hose attaches (inside the camper).

FYI, Montana and Outback are both Keystone campers. I bet they use the same part for the black-tank flusher.

Mine did the same thing, leaked all over the floor. Common problem with black tank flush systems. But my antisiphon/vacuum breaker valve was inside a wall behind the shower. Fortunately I could get to it by cutting a hole in the back wall of a cabinet on the opposite side of that shower wall.

Join the Montana Owners Club (MOC) forum for all questions about your Montana. Lots of expertise, experience, and friendly folks there.

Many Montana models, and probably other makes/models, have cheap back-flow preventers plumbed into the black tank flush systems. If your dealer replaces it with the same kind it will probably leak again some day.

Not all that uncommon. Black tank flush systems have an anti-siphon valve - back flow preventer (some times called a vacuum breaker). It is usually located inside a cabinet inside. Mine is under the bathroom sink.

It can leak if the water pressure is high or it can leak if it fails or it can leak just if it wants to leak..

Mine doesn't really leak, but sometimes it "weeps" a little. I just put a towel or dirty shirt from the laundry under it and all is good.

This is an example...it's not mine. (found the image on Google)



Well now, there you go Biscuit..you beat me to it again..
Is that picture that I pirated YOURS???

Backflow preventer is probably the cause of leak