Throughout summer, Sydney’s water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.

But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.This is great news for the city, but it comes with a big caveat.

Floodwaters will undoubtedly wash bushfire debris into reservoirs—possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.