There are actually a lot of choices out there for toilets to use in tiny houses. But pretty much all of them require you to think a little more about your waste than a normal flush toilet. With a flush toilet, it’s out of sight, out of mind. With toilets in tiny houses, you’re rarely hooked up to a black water system so the toilet requires a little more work. Here are the options I know of:
RV. RV toilets still use water like a flush toilet, but they are foot pump operated and you’d need a tank. You’d also have to empty that tank. I don’t know of any tiny houses that use an RV toilet.
Incinerating. I don’t know much about this one because I’d rather not burn my poo, but apparently there’s no smell. However, they’re expensive (upwards of $1500) and they use a lot of energy. I’ve seen an incinerating toilet in one tiny house online.
And composting, the most popular and diverse. These can range from around $10 to $1800. I’m planning on buying The Humanure Handbook and reading more on the subject, but from my understanding, your toilet is a container. Basically you add sawdust or another filler to help the composting process and to cover smells. Then when the container is full, you take it outside and add it to a compost pile and it will turn into soil after about a year. Some people just use a bucket, some wood, and a toilet seat. Then there’s Loveable Loo and Nature’s Head. Some models involve a hand crank and bigger toilet so the composting can happen inside. Some involve a vent. Some people buy a urine separator. I personally like the Serparett toilet, which is a little different because you don’t use a filler. It’s of course one of the most expensive ones, but compare the price of a waterless toilet to the cost of an entire septic system… This post convinced me that this is the one I want: http://tinyhousebuild.com/composting-toilet-options/
I would never have given toilets a second thought had I not needed to consider them for my tiny house build, but now I find our current system ridiculous. We are literally shitting in CLEAN DRINKING WATER just so we don’t have to deal with poop! That’s insane! And then we still have to process the black water somehow, so why not just save ourselves the clean water and the extra work by COMPOSTING? Mother Nature already has a way better system than ours; we should use it. I don’t know how composting toilets would work on a larger scale, but I’ll be glad to save water in my tiny house by using a waterless toilet.