I have a camper van with a separate holding tank for the little kitchen sink. It comes out to a 'gate' and then down to a hose bib ending(you could attach a garden hose). It has been fitted with a screw on cap that allows the grey water to drip as you are going down the road. <br><br>Well I have never been able to leave well enough alone. I got to thinking, gee that is a kitchen sink, I bet particles have gone down in there and might be trapped behind the cap. So I removed the cap and then opened the gate. The sludge that came out of there was incredible! I was glad that I released it somewhere out of the way because it stunk to high heaven! I patted myself on the back on doing a good job and got back to packing.<br><br>I went in to the van to rest about an hour later and the stink drove me back out quickly. I felt really guilty that my little dog had been in there with that sort of smell. So I rushed down to the store and bought some of the anti-stinky stuff for RV holding tanks. Nope, not making a dent in the stink. I ran water down into the holding tank along with the anti-stinky stuff. The air is now breathable as long as you breathe through your mouth. I plan on running some more water down in the holding tank and drive a ways and slosh it around good and then dump it. Then refill, drive back to the house and dump it again.<br><br>Any suggestions for killing the smell?