Envis Centre, Ministry of Environment & Forest, Govt. of India

Printed Date: Saturday, July 13, 2024

Two-pit System

Sulabh flush compost toilet is eco-friendly, technically appropriate, socio-culturally acceptable and economically affordable. It is an indigenous technology and the toilet can easily be constructed by local labour and materials. It provides health benefits by safe disposal of human excreta on-site. It consists of a pan with a steep slope of 25°-28° and an especially designed trap with 20 mm waterseal requiring only 1 to 1.5 litres of water for flushing, thus helping conserve water. It does not need scavengers to clean the pits. There are two pits of varying size and capacity depending on the number of users. The capacity of each pit is normally designed for 3 years’ usage. Both pits are used alternately. When one pit is full, the incoming excreta is diverted into the second pit. In about two years, the sludge gets digested and is almost dry and pathogen free, thus safe for handling as manure. Digested sludge is odourless and is a good manure and soil-conditioner. It can be dug out easily and used for agricultural purposes. The cost of emptying the pit can be met partially from the cost of manure made available. Sulabh toilet can also be constructed on the upper floors of buildings. It has a high potential for upgradation, and can later be easily connected to sewers when introduced in the area. Sulabh has so far constructed over a million individual household toilets in different parts of the country.


Advantages of Sulabh Toilets


  • Hygienically and technically appropriate, and socio-culturally acceptable.
  • Affordable and easy to construct with locally available materials.
  • Design and specifications can be modified to suit householder's needs and affordability.
  • Eliminates mosquito, insect and fly breeding.
  • Can be constructed in different physical, geological and hydrogeological conditions.
  • Free from health hazards and does not pollute surface or ground water, if proper precautions and safeguards are taken during construction.
  • Can be located within the premises as it is free from foul smell and fly/mosquito nuisance etc.
  • Can be constructed on upper floors of houses.
  • Pits are generally designed for 3-year desludging interval, but if desired, it can be designed for longer periods or it can be reduced even to two years.
  • Maintenance is easy, simple and costs very little.
  • Needs only 1 to 1.5 litres of water for flushing, while conventional flush toilet needs 12 to 14 litres of water.
  • Needs less space than a septic tank toilet system.
  • Does not need scavengers for cleaning the pits or disposal of sludge. This can be done by the householder.
  • Makes available rich fertilizer and soil conditioner.
  • Can be easily connected to sewers when introduced in the area.
  • A low volume flushing cistern could be attached to avoid pour flushing.

Sulabh flush compost toilet does not cause water pollution. When constructed in homogeneous soil, horizontally, bacteria do not travel more than 3 metres, and vertically the seepage is not more than 1 metre. To this is to be added the precaution that the toilet is built at a safe distance from the source of water, keeping the above points in mind. If there is a tube-well or hand pump sunk, the first joint should be lower than the limit of the vertical seepage. No vent pipe is needed since the gas gets absorbed in the soil facing the chamber, as the brick lining inside is in lattice formation. The parameters change depending upon the coarseness of the soil and the type of terrain where the toilet is being constructed. Depending on the availability of space, the shape of pits may be designed. It may be rectangular, circular or linear in shape. It fulfills all the seven conditions of a sanitary latrine laid down by the WHO. (Excreta Disposal for Rural Areas and Small Communities by E.G. Wagner & J.N. Lanoix, WHO, 1958, pp. 39).


  • The surface soil should not be contaminated.
  • There should be no contamination of ground water that may enter springs or wells.
  • There should be no contamination of surface water.
  • Excreta should not be accessible to flies or animals.
  • There should be no handling of fresh excreta; or when this is indispensable, it should be kept to a strict minimum.
  • There should be freedom from odours or unsightly conditions.


The method used should be simple, inexpensive in construction and operation.




Source : Sulabh International Social Service Organization