Bighorn waste tank

[jayc]

We leave the gray tanks closed and then use the water to rinse the drain hose after backflushing the black tank. No need for a P-trap.

 

[Lou_and_Bette]

We leave the gray tanks closed and then use the water to rinse the drain hose after backflushing the black tank. No need for a P-trap.

Same thing I do! On the Escapees forum there have been posters who reported an infestation of "sewer flies" in their grey tank due to leaving their grey tanks open to the main system. Not taking any chances so just dump grey tank after a couple of showers.