we have NEVER needed our blue tote tank for the black water.
we strictly use it for gray water since we have never gotten even close to filling the black tank before leaving the campground.
heck, we go 2-3 weeks of camping before the black tank is even close to needing to be dumped.
by that time, we've been to 3-4 campgrounds.
you have to be in one spot for a long time to fill a 25 gallon black tank.
but a gray tank can easily be filled in just a few days.
if you have one of those tiny black tanks, then that's a different story.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC