Wastewater management

Wastewater is considered to mean sullage, i.e. waste water that does not contain excreta or toilet wastes, except those arising from soiled bodies and clothing (Cairncross and Feachem, 1983). Therefore for the purposes of this Chapter, the term wastewater does not include sewage or rainwater.

Associated risks

Although wastewater may not pose such obvious health risks as excreta or medical waste, there are several indirect risks which should be considered. It is necessary to provide appropriate wastewater management systems in order to:
  • minimise breeding grounds for water-related insect vectors (e.g. mosquitoes);
  • prevent erosion of shelters and facilities;
  • prevent wastewater entering pit latrines or solid waste pits;
  • prevent pollution of surface or ground water sources; and
  • allow safe access to shelters and facilities.
Inappropriate systems, as well as lack of intervention, can increase some of these risks rather than reduce them. Systems involving standing water may inadvertently increase mosquito populations and infiltration systems may lead to the pollution of groundwater sources. Although the quality of the wastewater may not pose a direct risk to humans (assuming it is not ingested), where wastewater intercepts excreta or refuse disposal sites the risk of disease transmission can increase greatly. Wastewater which spreads toilet wastes or refuse will also spread the likelihood of direct human contact with disease-causing pathogens. This is especially the case where children play or people bathe in the watercourse into which the wastewater is disposed of. Wastewater can also pose considerable environmental risks, especially where it carries significant components of oil or detergent-based products, and where final disposal sites become stagnant. For this reason it is sometimes necessary to treat wastewater prior to disposal in the environment.

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