Originally Posted by BeagleMan
Well, thats good to know! No one has ever mentioned that aspect! I will certainly remember that.
We do not have a backflow issue if the drain is closed. We did however decide to leave it open after one use. We know our usage, timelines etc. for dumping tanks. We keep them on the same timeline vs running out to dump (rain, wind, snow etc.) whenever one might get full.
On wash day the gray tank valve is open and we do our weekly wash - no muss, no fuss then close. The rest of the time is normal then I dump on "dump" day. To leave the drain closed would totally put "drain day" into a "what is it, where are we" kind of mode most of the time. Much easier ways to handle it.