Many tiny homes use composting toilets. These don’t require flushing or even plumbing. Instead, they break down waste into soil-like compost that homeowners empty on a regular basis.
Composting toilets are inexpensive, waterless, and easy to use. However, they are not always accepted in zoning regulations, so you need to make sure before you build that you won’t be required to have a flushing toilet. If you have to later install a flushing toilet, you will also need to install an expensive plumbing system, and may end up spending thousands of dollars.
You will also need a sewage connection. If you have a mobile tiny home, and plan to move around or travel and stay in RV campgrounds, you may discover that many RV parks don’t offer sewage hookups.