It is a challenge that will continue to intensify as the world undergoes rapid urbanization, industrialization and increasing demand for meat and other foods unless decisive action is taken says a new United Nations report released today.
Urban populations are projected to nearly double in 40 years, from current 3.4 billion to over six billion people - but already most cities lack adequate wastewater management due to aging, absent or inadequate sewage infrastructure.
The new report, called Sick Water?, says some two million tons of waste, estimated to equal two or more billion tons of wastewater (see notes to editors) is being discharged daily into rivers and seas spreading disease to humans and damaging key ecosystems such as coral reefs and fisheries.
Wastewater is a cocktail of fertilizer run-off and sewage disposal alongside animal, industrial, agricultural and other wastes.
The report says that the sheer scale of dirty water means more people now die from contaminated and polluted water than from all forms of violence including wars. Dirty water is also a key factor in the rise of de-oxygenated dead zones that have been emerging in seas and oceans across the globe.
Yet many of the substances that make wastewater a pollutant - for example nitrogen and phosphorus - can also be useful as fertilizers for agriculture. Wastewater can also generate gases to fuel small power stations or be used for cooking.
The report notes that already some 10 per cent of the world's population is being supplied with food grown using wastewater for irrigation and fertilizer and with better management and training of farmers this could be increased substantially.
The report, launched to coincide with World Water Day, goes so far as to say that the concentration of nutrients in wastewater 'could supply much of the nitrogen and much of the phosphorous and potassium normally required for crop production. Other valuable micro-nutrients and organic matter contained in the effluent would also provide benefits'.