WEDC Technical Brief No. 32: Drainage for improved health

The principle function of drainage is to remove unwanted water from an area as rapidly as possible. Good drainage is critical to the general well-being of a site. Lack of adequate drainage causes rapid deterioration of road and path surfaces, restricts pedestrian and vehicular movement, results in damage to buildings and their contents, and creates generally insanitary conditions including potential sites for insect breeding.

The requirements are for:

• Drainage of sullage, that is, household wastewater which has been used for washing, cooking or cleaning purposes, but which does not contain excreta;
• Drainage of stormwater, that is, water which runs off the buildings and land as a result of rainfall.

Separate sullage drainage is not required if sewerage is used as the system of sanitation; all sullage can be discharged into the sewers.