It’s a technology with the potential to ease California’s colossal thirst and insulate millions from the parched whims of Mother Nature, experts say. But there’s just one problem – the “yuck factor.”

As a fourth year of drought continues to drain aquifers and reservoirs, California water managers and environmentalists are urging adoption of a polarising water recycling policy known as direct potable reuse. Unlike non-potable reuse – in which treated sewage is used to irrigate crops, parks or golf courses – direct potable reuse takes treated sewage effluent and purifies it so it can be used as drinking water.