Your holding tank can't be backing up unless...
...it's full to overflowing...there's no way the contents of the tank can "jump" up into the tank intake/head discharge line. However, it is possible for heeling to send tank contents back into the head discharge line, and if it's downhill from the tank to the head, whatever gets into that line can run back into the toilet. Incomplete flushing also leaves waste to build up in the line, so any flush water that remains in the hose to run back toward the toilet will be dirty. Backpressure from a clogged tank vent will prevent complete flushing...a clogged--or partially clogged vent will also cause odor. Pat is right...bleach is a non-no. It's corrosive and destructive to seals and valves in your toilet. Let's find the cause(s) for your problems and correct them instead of throwing counterproductive "bandaids" at it. Is this a new problem--especially the odor out the vent? Or have you had odor out the vent since you bought the boat? Before you answer that, I suggest you read the articles--especially the one on odor control in holding tanks--in the Head Mistress forum Reference Library...they'll give you a better understanding of what's going on and what to look for on your boat. Then I can help you figure out what you need to do to correct it. Before
