Building a Compost Toilet Inside a Shed — Feasible?

Design Considerations

To build a compost toilet inside a shed, consider a well-ventilated design with a separate aeration chamber to facilitate decomposition and minimize odors. A humanure sawdust toilet system typically consists of a mixing tank, composting chamber, and aeration chamber. Aim for a mixing tank volume of 20-30 gallons (75-114 liters) to handle 1-2 people’s waste. The composting chamber should be at least 2-3 feet (60-90 cm) wide and 4-6 feet (1.2-1.8 meters) long to accommodate adequate carbon-rich sawdust for odor control.

Ventilation and Pest Control

Proper ventilation is crucial to prevent the buildup of methane and volatile organic compounds (VOCs), which can emanate unpleasant odors. Install a 2-3 inch (5-7.5 cm) diameter ventilation pipe with a fan to ensure air exchange between the composting chamber and the aeration chamber. Incorporate a pest control system, such as a mesh screen or a physical barrier, to prevent rodents and insects from accessing the composting chamber. Consider installing a roof vent or a solar-powered fan to enhance ventilation.

Maintenance and Upkeep

Regular maintenance is essential to ensure the compost toilet system operates effectively and safely. Schedule regular emptying of the mixing tank (every 1-2 weeks), and ensure the composting chamber is adequately aerated. Monitor temperature (aim for 130-140°F or 54-60°C) and moisture levels (aim for 50-60% moisture content) to facilitate optimal decomposition. Keep records of maintenance and composting progress to ensure the system is functioning correctly and safely.