Clean out pipe pressure.

[Drew1979]

Hello all, we just got back from our third trip in our new trailer. The camp spot did not have sewage hookups and we had to dump on the way out. When I uncapped the sewage pipe on our trailer to dump the tanks it exploded out maybe a 1/4 gallon of sewage (not a pleasant way to end a trip). Any ideas why there would be pressure in the dump line? We have three tanks and the valves were all shut when I pulled the cap to hookup the hose. Any suggestion would be much appreciated.

 

[DavidL]

Since both the black and grey tanks should be vented to the roof, there shouldn't have been any pressure other than gravity pressure. One or both of the blade valves must have leaked a bit past their seals, or someone left or temporarily opened the blade which then filled the dump pipe between the blade valve and the screw cap.

I would ensure that the vent is open to air on the roof if it truly "exploded".

 

[Drew1979]

Since both the black and grey tanks should be vented to the roof, there shouldn't have been any pressure other than gravity pressure. One or both of the blade valves must have leaked a bit past their seals, or someone left or temporarily opened the blade which then filled the dump pipe between the blade valve and the screw cap.

I would ensure that the vent is open to air on the roof if it truly "exploded".

Thank you for responding David, It exploded enough get my feet and lower legs wet. I am new to RVing and will search on how to check the roof vents