A couple of years ago I removed the corroded aluminum holding tank and replaced it with a new 3M(?) poly tank. I also replaced all hoses with head mistress recommended hoses. We are not heavy users and had the tank pumped several times each summer. Yesterday, in preparation of winter haul out, we took Endeavor to the local big time marina and had the tank pumped. Business was slow and the pump girl spent a lot of time pumping and rinsing the tank. After what seemed like a long time, she was still getting brown sewage water out of the tank: it would stop, it would bubble, and then it would draw more brown. After the third or fourth rinse, we decided that it was empty. The problem is that when I went below, there was a strong sewage oder. I have never experienced that before except when the tank was full. I wonder if this is normal or gives me something else to worry about this winter. I wondered if one of my hoses came loose but I can't figure how that would happen as each was double clamped. I also wonder if the thorough vacuuming may have cleared the hoses from the heads and allowed the oder to go back through the heads. I tired the "sniff" test in the heads and it did not seem as strong as in the vicinity of the tank. It likely is that this is the first time that the tank got thoroughly flushed and it just stirred up the gunk on the bottom. Any thoughts or suggestions or is this normal with a good flush. Thanks, Art Butler