Graham, I've only the portapotty. Hopefully someone with a marine head can chime in. I have no idea where the holding tank is located. Good luck! Lee -- View this message in context: http://rhodes-22.1065344.n5.nabble.com/Holding-and-water-tanks-tp45782p45803.html Sent from the Rhodes 22 mailing list archive at Nabble.com.