6. Integrating Water Quality into Urban Water Management and Planning While Addressing the Challenge of Water Security

In the face of growing water demand pressures, urbanisation, and climate change, freshwater resources are becoming scarcer and supply planners are turning to less traditional water sources, such as treated wastewater and urban run-off (stormwater), sources which may pose health risks to consumers. At the same time, traditional surface and groundwater resources are being subject to increased contamination, which contributes to water insecurity. How to address the water quality and public health dimension of urban water quantity challenges is emphasized in this chapter, especially through proper treatment and recycling of polluted run-off and wastewater, which, in the end, can achieve a two-fold benefit of increasing water supply (quantity) and improving the quality of available traditional freshwater resources. With the introduction of alternative sources however, and the delivery of fit-for-purpose water quality, it is crucial to both maintain and demonstrate the level of public health safety and protection in water supply. A systematic but flexible approach is needed to manage public health risks, either by framing and guiding the development of new supply schemes, or by assessing and validating the safety of existing schemes from contaminated sources. Quantitative Microbial Risk Assessment (QMRA) is a method that allows quantitative estimates to be made of microbial risks related to exposure of humans to water, either through drinking or other uses. In this chapter, the role of QMRA is described as a response to a 4-fold need, i.e. the need: (i) for technical guidance in the design of alternative supply schemes; (ii) for regulation to protect public health, both in traditional and alternative supply sources; (iii) for regulatory frameworks and institutions to enable innovation and development; and (iv) to assess new risks from innovative supply schemes and compare them to traditional water supply or other public health risks. Examples of water quality challenges in developing alternatives sources are given. Finally, the role of QMRA in balancing public health concerns with water availability issues and environmental, social, and economic factors in the decision-making process for water security planning is discussed.