12V Water pumps and cisterns

[plowhog]

When the rainwater hits your bacteria and microbe infested roof, those microbes will sail past any screen by the thousands or millions. The screens are for debris, not sanitary treatment. You can treat your water as suggested above. Personally, I might harvest rainwater for plants, etc. But I wouldn't brush my teeth with water that hit my roof first. There are many variables with water treatment and if things go haywire-- its not good.