Let me ask what may be a dumb question. I am going out for the first time this weekend with my TC and, since I don't have a gray tank, I'll be draining the sink into a 5 gallon bucket. When I am lea...
You could drain the black tank, close the valve, then dump the sink water down the toilet and drain the black tank again. This will flush it out somewhat. Some toss the sink water in the bushes. Check with your campground for rules. Happy Camping!