Bad tank water

It's something that I've suspected for a long time.
Now, it has been proved; that rainwater stored in tanks is unfit for drinking.
Researchers at Flinders University have found that more than 50% of tank water tested contains the dangerous E. coli bacteria.
E. coli causes vomiting, diarrhoea and stomach cramps.
Yes I have rainwater tanks, but I only use the water for the garden.
I would even consider it for drinking.
Just think about all the bird and possum and rat poo that gets washed into the tank!