Rainwater starts out clean, bacteria and virus free, but as soon as it hits a collecting surface like a roof top, dangerous bacteria can enter the water.
Animal and bird droppings, dust, dirt and decaying vegetable matter like leaves can contaminate tank water. Each of these sources of contamination can lead to dangerous bacteria entering your water supply, like E.Coli and streptococci.
The Acquasafe dosing product makes water safer by destroying virtually all bacteria and virus, leaving tank water clean enough to drink. Davey recommend using Acquasafe with a one micron filter at the drinking water tap for cyst reduction.
Davey has a dedicated water treatment website - please click through for more information.