Why Waste Water?

WHY WASTE WATER? Requiring all water to be drinkable, regardless of its planned use, wastes water, energy and money. Through cascading use of water, we can reuse water in multiple ways. Sewage Grey Water Treated Wastewater Potable Water O Rainwater I Surface Water Ground Water ENERGY FOR WATER Treating water uses a lot of electricity. CLIMATE CHANGE Energy costs can make up over 40% of Extreme weather, including a water utility's operating costs. droughts and floods, will mean more uncertain water supply. By 2050, more than 1 billion people will live in cities without sufficient water. WATER FOR INDUSTRY Almost 90% of power generation is water intensive. Treated wastewater can WASTEWATER TREATMENT replace freshwater for some industrial Up to 90% of wastewater in developing uses, including energy generation. countries flows untreated into rivers, lakes and coastal zones. Wastewater can be treated and reused for agriculture, energy generation and environmental use. WASTEWATER FOR AGRICULTURE Treated wastewater can be used to grow food. In many lower-income countries, raw sewage is used for food production, which can cause the spread of disease. DIGESTER AQUIFER RECHARGE Wastewater creates gas Managing groundwater through aquifer that can be turned into recharge can give cities a 'vwater buffer' to deal with uncertain water supply and may energy using digesters. During the next 20 years, reduce subsidence. cities in developing countries will have to meet the demand of 70 million more people each year. HOUSEHOLD WATER USE Rainwater captured from rooftops can be recycled to fill toilets and to water gardens, saving water and energy. WHY DOES WATER REUSE MATTER? The global population is expected to pass 9 billion by 2050, driving up demand for water for use in homes and buildings, agriculture, industry, and power. As water demand grows, cities are forced to rely on water sources that are further from the city-and more expensive to tap. Today, agriculture accounts for 70% of water use globally, followed by industry (20%) and domestic water use (10%). EXAMPLES OF REUSE IN ACTION: Stockholm, Sweden Water in Hammerby Sjöstad is used five times: Drinking Water Wastewater treatment plant separates sludge for to make biogas The residual sludge is sold to farmers as fertilizer. IL Cleaned wastewater is used in the district heating plant where heat-exchange captures the heat Cold wastewater is used to cool public buildings Windhoek, Namibia All potable water resources within a radius of 500 kilometers have been fully exploited, and the city is growing rapidly. Windhoek now relies on four main sources of water: Surface water from dams Durban, South Africa Groundwater Recycles wastewater for industrial use, meeting 7% of the city's water demand. Treated wastewater for irrigation Industries reduce their costs by purchasing reclaimed water at a lower price. Reclaimed water purified to be drinkable THE WORLD BANK Learn more at www.worldbank.org/water I Infographic Design By WebpageFX Sources: ESMAP (2012) A primer on energy efficiency for municipal water and wastewater utilities. World Bank, Washington DC. I McDonald et al (2011) Urban growth, climate change, and freshwater availability. PNAS, 28 March 2011. I IEA (2012) International Energy Agency (IEA). 2012. World Energy Outlook 2012. International Energy Agency, Paris. I UNEP (2010) Sick water? The central role of wastewater management in sustainable development. I Scheierling et al (2010) Improving wastewater reuse in agriculture. World Bank, Washington DC. I Rodriguez et al (2013) Thirsty Energy. World Bank, Washington DC. I 2030 Water Resources Group (2009) Charting our water futures IJacobsen et al (2012) The future of water in African cities: Why waste water? World Bank, Washington DC.