Black tank flush leak

[Roaminaround]

I have a 2608BS. This morning when I emptied and flushed the black tank I noticed a fair amount of water spilling out of the connection outside to the flush input. I hand tightened it and there was still a fair amount leaking out. A couple minutes later my wife alerted me to water on the floor of the bathroom directly inside of the flush connection outside. Plenty of water was getting into the tank but there was some kind of obstruction near the outside connection. I looked and didn’t see a back flow valve like on the city water connection. What could be obstructing it and causing the leak?

[01tundra]

Originally Posted by Roaminaround

I have a 2608BS. This morning when I emptied and flushed the black tank I noticed a fair amount of water spilling out of the connection outside to the flush input. I hand tightened it and there was still a fair amount leaking out. A couple minutes later my wife alerted me to water on the floor of the bathroom directly inside of the flush connection outside. Plenty of water was getting into the tank but there was some kind of obstruction near the outside connection. I looked and didn’t see a back flow valve like on the city water connection. What could be obstructing it and causing the leak?

There's usually a anti-siphon check valve somewhere in the bathroom, our is under our sink. They are notorious for leaking....

[Roaminaround]

I did some poking around. Found the anti siphon valve under the sink. There was water around it. Hooked things up and ran it while my wife watched the valve. This time it worked with no backflow of water. I guess it was temporarily plugged inside the tank. Watched a YouTube video where the guy took apart the end inside the tank after testing his backflow valve and found it to be operational. Now I know how this system works.