Wastewater reuse and public health

Treated municipal wastewater is being increasingly recognised as a valuable and sustainable resource that can supplement more conventional water supplies. This is particularly important as population growth and climate change are predicted to place additional strain on often already limited conventional freshwater supplies.

In many parts of the world water reuse systems have already been successfully implemented and the practise has the potential to augment potable water supplies, provided that the potential risks to human health are fully understood and consistently controlled. Of particular concern are pathogenic microorganisms such as enteric viruses commonly found in municipal wastewaters.

However, there is no current consensus in the UK as to what standards are most appropriate to govern wastewater reuse, although the World Health Organisation (WHO) has developed guidelines on the safe reuse of wastewater in agriculture, and international reuse guidelines are available. Therefore, prior to implementing a water recycling scheme to counter current water supply issues, a greater understanding of human health risks is required.

As such, this project directly assessed the potential human health risks associated with the augmentation of source waters with treated municipal wastewater using a Quantitative Microbial Risk Assessment (QMRA) approach. This approach aimed to determine the minimum level of wastewater treatment required in order to safeguard human health, prior to the release of reuse waters upstream of drinking water abstraction sites.