rainwater storage life in drum?

Greetings in the name of Yeshua. I am planning on purchasing a large drum, rubber, I believe, to collect rain water in.

How long can water remain in a drum, and still be (a) drinkable, (b) usable for bathing?

Thank you.

That depends....

- What colour is the drum? Tanks that don't let sunlight in stay sweeter for longer (with clear tanks you just end up with a tank of algae)
- Is the tank buried? Buried tanks stay a more stable temperature (and obviously the colour/opacity doesn't matter if its underground!)

If its drinkable straight from the tank- that partly depends on how the rainwater was collected and what kind of filters it goes into before the tank- I wouldn't be drinking rainwater straight off my 120-year-old slate roof, with the associated pollution of living near an industrial area, ever. Metal rooves or slates are usually better than concrete tiles, which are better than asphalt felt. Is there a first flush mechanism to dispose of the first, probably dusty bit of rain? Is the roof overhung by large amounts of deciduos trees?

Sorry its not really a straight answer

Thank you for your kind answers. No, I would probably be directing the rain water from a plastic or metal roof (not sure which to get), into a drum as the one on the link (half that size).