Which water quality for which uses? overcoming over‐zealous use of the precautionary principle to reclaim wastewater for appropriate irrigation uses

The growing conflicts over water resources look set to worsen in the context of climate change. High quality groundwater resources ideally reserved for domestic use are diminishing especially where urban centres are growing, as treatment facilities cannot always keep up. The farming sector could manage water quality and quantity better to produce food sustainably, keeping economic activity in rural areas. Purification techniques are progressing in efficiency at growing cost, removing the polluting load from effluent which is potentially useful for agriculture. Competing domestic and agricultural water uses can in fact be complementary, as can be seen in green belt of megacities. Policy making based on the precautionary principle is developed from existing regulations and guidelines. Because of the lack of scientific results, policies most often confuse prevention and precaution. A balanced application of the precautionary principle would enable a rational development of reuse schemes, preserving good quality resources and taking benefit from disposed of minerals for crops. An economic approach along with risk assessment would avoid disproportionate costs to gain security. Consistent information and training should be organised to enhance public and worker awareness of risk management.