Composting Toilet

I would not want to camp in a place where the immediate prior occupant emptied the grey water tank. That is a health hazard. Just because you can do something does not mean that you should do so.

Again to reiterate what I have posted elsewhere, once grey water is put in a tank, it has to be treated as if it were black water in NC. You can use grey water only in a drought and then by hand watering non-food trees and shrubs. So, you could take your dish pan and water a shrub with it during a drought, but not during "normal" times. Put it in a tank, and then you would need to have a water treatment plant to run it though before being able to use that water. The grey water tank can stink pretty badly because bacteria also grow there. That is why it has to be considered the same as black water.

Dumping gray water is actually legal in most states, of course there are restrictions and caveats so best to consult local laws before doing so. New Mexico, for instance, allows 200 gallons of gray water to be discharged without a permit. BLM usually allows gray water dumping on surface but National Forests and Army Corps of Engineers do not. Best to know your options.

The benefit of so called composting toilets in rvs is not having to go to a dump station. But that assumes you empty your gray tank on the surface, which is illegal most places. I could see getting one if you were camping on private property where you could dump your graywater on the surface. Otherwise not so much.

I put composting in quotes because RV compostjng toilets aren't really true composting toilets, that usually takes many months and a big storage chamber. The RV "composting" toilet is more a way to store semi dry material for a little while until you can dispose of it. For that reason the RV composting toilets have to have a way to separate urine and feces, which are then disposed of separately. There is also a 12v vent fan to minimize odors. IOW, it's significantly more complex than having a flush toilet and blank tank.

You also typically have to add coconut choir or other similar material to balance out the organic content.

Another alternative to consider is the cassette toilet, which is basically a port a pot with a separate storage container you access from outside the trailer. That can then be dumped in a regular toilet or at a dump station, giving you options without the hassle of the "composting".