[Dave W]

What I found with our HC is that while the black tank drains slowly, it's really not a problem. My fix is to install a Valterra knife valve at the outlet. Keeping it closed, pull the black tank handle and let it fill the line then dump it out. Next, I pull the gray bathroom tank handle after closing the Valterra valve, leaving the black tank valve open. This in turn will back flush the black tank. Wait a minute or two then open the Valterra valve once more. I then close that BR gray tank valve as well as the Valterra and open the kitchen tank to, again, backflush the black tank. I then open the Valterra again after a minute or so.


Now, will that completely clean the black tank - not really as there will be an inch of sludge on the bottom that will only come out with an aggressive multiple flush but it for sure drags a lot more out then just opening the black tank valve and hoping it fully dumps. Using the built in tank flusher is barely worth the effort but every little bit helps.



Of course, if you totally fill that black tank before dumping, will go a long way to totally empty it them my method is a bonus..


This has worked for me since 2015.