The tanks also supply water to fill the spray tanks and can supply water at 100 litres/min. With recent rain there was 28,000 litres in the tanks when a possum climbed up the post supporting the spray filler hose and opened the fill valve, sometime late on Tuesday night.
Now, at 100 litres/min it would take four hours and forty minutes to empty the tanks. By morning that had happened. The possum is the only plausible theory.
So, somewhere on Providence, there is a possum with a price on its head.