Build Your Own Composting Toilet: Manual & Guidelines

This manual offers detailed construction guidelines for building a composting toilet (CT) suitable for areas with limited fresh water, near-surface groundwater, or sensitive environments like reefs. Site selection involves choosing a location away from water sources; preparation includes digging a 15 cm deep foundation, filling with compacted coral/stone, adding sand and plastic sheeting, and laying 6mm rebar. Concrete mixing uses a specific ratio, poured for the foundation slab. Chamber walls are built with concrete blocks filled with mortar or concrete mix, leaving spaces for drainage pipes to an evapotranspiration (ET) garden. The ET garden is constructed with a material list including gravel, pipes, and plants for liquid dispersal. Floors are formed and poured with options for different designs, including false floors for compost access. Access doors, toilet pedestal construction from wood or blocks, and a superstructure house complete the build. Technical drawings illustrate all steps. Composting requires adding dry organic matter like leaves or wood shavings after each use to facilitate decomposition; chambers are built above ground, necessitating stairs or ramps. The process yields usable compost after maturation. Construction emphasizes durable, low-cost materials like coral blocks and rebar, ideal for community or regenerative projects in island or permaculture settings. Steps include mixing concrete (1:3:3 cement:sand:aggregate), forming slabs, building walls with middle row rebar between chambers, and integrating drainage. This provides concrete, actionable plans for owner-builders, covering foundation to roof, ensuring hygienic, waterless sanitation with practical ET for liquids.