Background

In India only 400 cities have sewerage networks that are fully or partially connected to treatment plants (Niti Ayog, 2021). The other cities are fully dependent on onsite sanitation systems. In these cities, toilets are usually connected to septic tanks. The design, construction and maintenance of septic tanks are, typically, the responsibility of households. These septic tanks are not properly constructed and in most cases the norms are not followed. Improperly designed and constructed septic tanks can lead to a reduction in treatment efficiency and hazardous gas accumulation within the tank. Such gases include methane, hydrogen sulphide, carbon dioxide, and sulphur oxide. These deadly gases when inhaled for significant periods of time and could be fatal. As many as 347 people have died while cleaning sewers and septic tanks in India in the last five years. When the septic tank is full, the final call is made to a desludge operators (DSOs). The DSOs are typically from the informal sector without adequate knowledge on regulations, and safety precautions.