Sewer Flush Leaks

That sewer flush goes to black tank only.
Water goes in thru connection then UP to/thru a backflow preventor then DOWN to sprayer in black waste tank.

The backflow device is typically installed under bathroom sink cabinet as that area is high enough and close/above black tank.





High water pressure can cause them to leak out under open 'cap' area.

Also, some have been installed backwards which will allow them to run water out everytime water is connected.

I assume you aren't talking about that bunch of water that comes out from the anti backflow unit when the water is turned off?
bumpy

Where is the leak?
Sewer Flush systems have a back flow / anti-siphon valve. Most often that is where they leak.

Mine is against the wall inside the bathroom vanity cabinet. If the water pressure is really high mine sometimes 'weeps' a little water when I am flushing the tank. I just put a towel under it to soak up what does leak.