[tentcamper]

+2 what bill said about the black water. There are 2 valves. One on the toilet at the bottom and one to dump one you drop the black water into the pipe.

Several of us the seal on the valve at the toilet developed a leak and it would fill the pipe without the valve being open. Its a simple fix to replace the valve seal. But you might want to fill the toilet water with both valves closed to make sure its not going to leak and fill up the pipe outside, which could freeze when using the camper. Let it sit for a day or so. Then remove the drain cover outside, put a 5 gal pail under it and open the outside large valve. It should have almost no water in it. If you have water you have a leaky seal.

Close the outside valve. Pull the valve under the toilet and go outside and open the large valve. It will come out fast so have your pail ready to catch it. You will need to shut the outside valve it because there will be more water than the 5gal pail will hold.