There's many designs that are used all over. I like my cabin's privy and going to do some upgrades to make it odourless: solar powered exhaust fan. In the dese

There's many designs that are used all over. I like my cabin's privy and going to do some upgrades to make it odourless: solar powered exhaust fan. In the desert where the water table is hundreds of feet below you (and getting lower!), groundwater contamination isn't exactly an issue. But there's also composting toilets and incinerating toilets that exist. A fancy incinerating toilet costs like $5k (Cinderalla toilet, I'm looking at you!), but I'm sure they'll cost a fraction of that in time. But there is an electricity cost to each 'flush' then.