Rain water into header tank

[Mr Pipples]

Pondering on topping a header tank up with rain water - this header fills a cylinder that will supply showers, bath and c.heating. Would I get away with a simple down-pipe filter to clear the rainwater up enough to work in this system or would it need bringing up to potable standard? Cheers.

[northern installer]

you mustnt allow the rainwater to be able to contact the mains water;possibly causing cross contamination,thats in the water bylaws;and if you are going to do anything more than flush toilets,it will need to be treated to potable standards;dont forget,your roof will be covered in bird poo,and bird poo contains,amongst other things,salmonella ,plus anything else the seagulls have ingested at the local sewage works,landfill site,or n plant.in short,not recommended!