'19 Residence blackwater flush leaking

[katiegreeniz]

We have a 2019 Keystone Residence 40LOFT. I just went to flush the black tank and when I connected the hose to the black water flush-water started leaking inside the camper coming out from underneath the cabinets in the bathroom and the kitchen. This has never happened before-any ideas??

[flybouy]

There is a backflow prevention valve mounted high under the sink. It has failed and I'd leaking. It's a common issue.

[JRTJH]

Originally Posted by katiegreeniz

... This has never happened before-any ideas??

Oh Contrare, mon Ami..... It happens hundreds, maybe even thousands of times every year. The anti-siphon valve is very fragile and is subject to freeze damage as well as "sudden pulse" pressure damage. It will not survive freezing with any water in the valve and few people "winterize the black tank flush line". Most people learn, after one such incident, to just remove the valve during winterizing and shake all the water out of it, store it (disconnected) and reinstall it in the spring.

Additionally, if, when flushing the black tank, you turn on the water supply too quickly, you can cause the anti-siphon valve assembly to "slam into the stop" with too much force and cause it to break. Always turn the water supply on slowly, so the valve won't slam into the stop.

So, either condition will cause the valve to start leaking and flood the vanity. Fortunately, Keystone seems to have stopped installing the valve in the shower wall. When it was there, significant damage could occur from a leaking valve before it's even discovered. With it under the vanity, about the worst that happens is a "cleanup of clear water" and a ruined (soaked) roll of toilet paper.....

Get a new valve from any RV parts store or consider an upgrade to a brass valve and associated fittings that can be found at Lowe's, Home Depot or any hardware store.

It's a common problem, one faced by nearly every RV'er who has been towing trailers for any length of time. Welcome to the "wet vanity club"...

[skids]

Originally Posted by JRTJH

Additionally, if, when flushing the black tank, you turn on the water supply too quickly, you can cause the anti-siphon valve assembly to "slam into the stop" with too much force and cause it to break. Always turn the water supply on slowly, so the valve won't slam into the stop.

Wise advice.

[Bill-2020]

Originally Posted by JRTJH

It's a common problem, one faced by nearly every RV'er who has been towing trailers for any length of time. Welcome to the "wet vanity club"...

I don't wanna be a part of that club... That valve is so far up the backside of our sink, the sink will have to come out to gain access to it. Advise of slow turn on noted. Thanks!

[MerlinB]

Originally Posted by Bill-2020

I don't wanna be a part of that club... That valve is so far up the backside of our sink, the sink will have to come out to gain access to it. Advise of slow turn on noted. Thanks!

Not necessarily. When I found mine leaking I was able to pull it to the side far enough to see that it was leaking because the fittings were barely hand tight. Judicious use of some slip joint pliers solved the problem.