Originally Posted by BatDude
The fellow suggested I do not do that, as he makes his living charging top $$$ cleaning out folks RV black water tanks that have been drained continually. This leaves solids behind that do not flow out as the liquids drain continually.
So eventually a lump of solids hardens and needs to be cleaned out at premium prices.
His recommendation is to let the tank fill then drain as normal and all will be drained AKA Flushed at one time.
He is correct! Just before dumping my black tank I always make a point of filling it right up with water - more liquid in the tank will result in a much better flush out when you open the valve up to dump.
On my grey water tank I do have the cap with the smaller garden hose connection which I only use when I am draining the tank off into my portable waste container which I normally only use when dry camping
and keeping the trailer parked in one location for an extended time. If emptying the grey water tank at a dump station I use the large slinky hose. When you use the smaller hose there is not enough water flow and as a result you will probable end up with a build up of small dish washing bits or coffee grounds etc left behind in the tank. No matter how hard you try to avoid bits of stuff going down the sink somehow some always manage to go down it. If bits of stuff are left sitting in an empty grey tank in warm weather the tank may start to smell a little bit. I use a water tank wan
d to give both the grey and black tanks a good rinsing out before leaving the trailer parked unused for more than a few days, to make sure they are completely rinsed out and nothing is left behind.