Sanitation and Wastewater

The Impact of Sewage on the Marine Environment:

Domestic wastewater improperly discharged to freshwater and coastal environments presents a variety of concerns. The spreading of pathogens, suspended solids, nutrients, plastics and other debris, and toxic substances like heavy metals and persistent organic pollutants in cases where industrial effluents are mixed with municipal wastewater, affect adversely human health, threaten biodiversity and have a negative economic impact exacerbating poverty.

Damages associated with inadequate handling of wastewater may include:

• Human health impact i.e.: bathing in polluted water or through the consumption of contaminated shellfish;
• Ecosystem impact by increased nutrient and pollutant levels that lower oxygen levels;
• Economic impact through direct and indirect effects on both human productivity and marine life, and the economic sectors depending on it.

Some examples of the costs of inaction are:

• Higher direct and indirect costs caused by increased illness and mortality, e.g.:
  • The Global Burden of Human Disease, caused by sewage pollution of coastal waters is estimated at 4 million lost ‘man-years’ every year, which equals an economic loss of approximately 16 billion US$ a year;
  • Lost income and additional health costs from the 1992 cholera spread in Peru were estimated at ten times the annual national budget on water supply and sanitation.
• Higher costs for the production of safe drinking water and industrial water;
• Loss of income from fisheries and aquaculture;
• Other costs associated with the loss of valuable biodiversity;
• Lower income from tourism, as poor water quality and algae blooms deter tourists;
• Loss in real estate values, when the quality of the surrounding deteriorates.

Environmental effects associated with domestic wastewater discharges are generally local with trans-boundary implications in certain geographic areas. The commonality of sewage-related problems throughout coastal areas of the world is significant. Consequently, domestic wastewater discharges are considered one of the most significant threats to coastal environments worldwide.

The priority for action on sewage was identified by:

• The Global Programme of Action for the Protection of the Marine Environment from Land-based Activities (Washington, 1995);
• Seven regional workshops of Government-designated experts held in the period 1996 – 1998 in the framework of UNEP’s Regional Seas Programme and involving more than 60, mostly developing, countries;
• The UNEP Governing Council in decisions at its 20th, 21st and 22nd sessions.