WoodGlue wrote:
Rotten food, grease and bacteria have a pungent odor. You can try putting some fabric softener down your traps and see if that doesn't help.
WoodGlue
Minimize the food particles and grease going down the drain and your smell will go away. We wash dishes outside in a collapsible tub a little bigger than the sink after wiping out everything we can with paper towels. It's easier and eliminates this issue.
If that doesn't work for you, Do the same thing I do for the black tanks. After you dump the tanks, throw about a half a cup of Clorox down the drain and a cap full of the cheapest liquid water softener you can find and then put a couple gallons of water in there. Leave it in for the ride home to slosh around and it coats the tanks and your water level gauge and keeps it from stinking. Also recoats on the trip back to your next campsite and then gets dumped when you dump the tanks. Then Repeat.