One of our favourite institutional builds: the OTIS project from Green Mountain College, Vermont, USA. OTIS stands for Optimal Traveling Independent Space — a self-sufficient tiny dwelling on wheels, designed by students.

Tucked inside OTIS's compact toilet area: a We-Pee urine separator. Quietly doing its job in one of the more publicised tiny-house design experiments of the decade.
"We are now working on the second iteration of the concept. We are improving on certain things and reusing other concepts. One of the designs that worked really well is the composting toilet we designed using your urine separator."
— Simon James, Green Mountain College


The OTIS project was featured by Gizmag (now New Atlas) and remains a useful reference for anyone building a self-sufficient tiny house — not least because the composting toilet design has stood the test of multiple iterations.
For your own tiny house build
Tiny houses, vanlife conversions and off-grid cabins are some of the most common uses we ship separators for. The £31 original Urine Separator is the most popular choice — compact enough for tight spaces, easy to integrate into a custom-built box. For the full build guide, see how to build a composting toilet.