I hate saying this but if you only let people pee in your bathroom we just emptied ours on a gravel road or somewhere not on pavement. Essentially you aren't dumping fecal matter or chemicals if all you have is urine and dirty sink water in your tanks and maybe some toilet paper which is biodegradable so it's no worse than if you just peed outside or dumped some dirty water out. We tried to dump ours at a dump site if we could but unless you pass one on your way to or from Ames it really was our only option other than driving clear out of the way to do it. We're getting rid of our RV (it's really old too, 1977 and the tanks aren't exactly leak proof either) so this won't be an issue for us anymore. Got our money's worth of fun out of it but between the maintenance and all the extra work it takes to bring it to tailgate the time has come to sell it as soon as we can get it sale ready.