Figure 22: Global water withdrawal and waste over time.

Improving watershed management will be crucial and finding ways to reduce, optimize and recycle water will become increas- ingly essential in the future. Wastewater is already being used for irrigation and fertilization and can continue to expand this role, particularly for peri-urban or urban agriculture and home gardens. But maximizing water efficiency in the entire water chain including before water enters the cities, and reducing production of wastewater should be a primary goal throughout the entire management scheme.

WASTEWATER AS A MANAGED RESOURCE FOR IRRIGATION AND FOOD PRODUCTION

With proper management, wastewater can be an essential re- source for supporting livelihoods. Wastewater treatment and reuse in agriculture can provide benefits to farmers in conserv- ing fresh water resources, improving soil integrity, preventing discharge to surface and groundwater waters, and improving

economic efficiency. In the US state of California, 31 per cent of reclaimed water is used for crop or landscape irrigation. In Mexico, most of the wastewater from Mexico City is used in irrigation districts surrounding the city, notably the Tula valley. Untreated wastewater is often used in the informal, un- regulated sector and directly benefits poor farmers who would otherwise have little or no access to water for irrigation. Even untreated wastewater can improve soil fertility and reduce wa- ter contamination downstream, since the wastewater is not fed directly into the water flow but is first filtered through soil during irrigation. Through FAO’s Farmer Field Schools in developing countries, training in risk-reduction and man- agement strategies in safe food production and crop selec- tion have been implemented from International Guidelines (WHO-FAO 2006) to simple and adoptable ‘farm-to-fork’ techniques. Safe reuse of untreated and partially wastewater for agriculture production has been tested in Ghana and Sen- egal where various options at farm, markets, and food-vendor

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