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The total water withdrawal was estimated at 4 205 million m³ in 2002, with agriculture accounting for 79 percent of total water use. However there has been a significant decrease in water demand in agriculture following the introduction of the FTLRP, as well as in industry and mining due to the subsequent financial crisis. In 2007, the total volume of water allocation was estimated at 3 570 million m³ (WB, 2014), including 2 930 million m³ (or 82 percent) for agriculture (Table 6 and Figure 1). Actual water withdrawal is nonetheless much less than the allocated volume. In addition, since 2008 irrigation water withdrawal has declined dramatically. In all catchments, except Runde, less than 30 percent of the potential water available in reservoirs was utilized in 2010 (WB, 2014).
Some estimations consider that water withdrawal in 2010 was half the 2002 level, mainly due to a sharp decline in irrigation. These estimations used the data of 4 205 million m³ in 2002 from the AQUASTAT database as a starting point, including 3 318 million m³ for agriculture, and based on that estimated that it is 2 170 million m³ in 2010, including 1 660 million m³ for agriculture (AfDB, 2011). In that scenario, the 2002 water use level would be recovered in 2014-2015.
Finally, national data from the ZINWA seven catchment offices declare a total water withdrawal of 887 million m³ in 2014, including 700 million m³ for agriculture. These data, however, seem to be too low estimates considering the total population and the total irrigation areas and might partly refer to water consumption rather than water withdrawal.
Despite the fact that groundwater resources are limited, groundwater is the main source of water for more than 70 percent of the population in particular in rural areas. It's only since the public water supply network systems have become unreliable that groundwater demand is increasing also in urban areas (WB, 2014).
Water shortage, in particular in Bulawayo, the country's second largest city, sometimes restricts industrial activity (GoZ, 2012). So use of non-conventional water is of particular importance.
Wastewater is collected to semi-centralized wastewater treatment plants using conventional sewerage infrastructure, but storm water drains directly into rivers and reservoirs. It is estimated that about 194 million m³ of municipal wastewater was generated in 2012 in four major cities (Harare, Bulawayo, Mutare and Gweru) and only 95 million m³ treated in the 137 existing wastewater treatment plants in Zimbabwe (UNWAIS, 2012). However, these plants are currently operating at maximum 30 percent of the capacity, hence releasing raw or partially treated wastewater into rivers. Harare's wastewater pollution is being detected some 260 km away, while Bulawayo's some 100 km downstream (WB, 2014).
Because the major cities are often upstream of the main basins and water supply is usually installed downstream the city to increase the catchment yields, untreated wastewater returning to the catchments is most probably harmful for the same cities. On the positive side, treated wastewater is a significant potential source of water close to the cities.