wa8yxm wrote:
In addition to the faucet, which.. The sinks, should not drain into the black tank, they should drain into the gray or wash tanks, ONLY the toilet should drain into the black..
that said, Some Rv's they plumb incorrectly so the sink does drain into the wrong tank.
Still.. the problem is a faucet, if it is the black tank that is filling, I'd suspect the toilet.
On the Monaco coaches, some have the bathroom sink draining in to the black tank in such a manor to help wash away the dreaded pyramid of crap.