Sulabh Flush Compost Toilet

The Sulabh Flush Compost Toilet is designed as a two-pit system to ensure that one could be used continuously to contain waste while the second allows waste to decompose and become fertilizer. The toilet pan has a steep slope (25°-28°) and the plumbing uses a water-seal (20 mm) to prevent odours. Water conservation was considered during the design, so each flush only requires 1 – 1.5 liters of water. The two pits are sized based on the number of users, designed with a lifetime of 3 years of use per pit.

Operation and maintenance is performed by Sulabh and funded through a pay-per-use model, while maintenance in low-income areas is cross-subsidized with income from the toilets in wealthier, busier areas.

Each pit is designed to be filled for 2-3 years. If the dual-pits are emptied and used effectively, the toilet is expected to operate for an extended period (with pits reported to operate for 40 years).

An assessment was performed by the United Nations Development Program (UNDP) in 2006 to assess the operation, impact and financing of Sulabh International within the context of the sanitation landscape in India. This included an examination of the organisation’s mode of operation, its impact on health and hygiene, and the eradication of scavenging.

If the pits are not constructed properly and well-sealed, there is the possibility of groundwater contamination. In addition, the time needed for waste digestion before it becomes pathogen-free is still debated. Furthermore, the product is deemed not applicable in hard rock environments due to potential groundwater contamination.