Harvested rainwater isn’t really great to drink, but if you are without your main water supply for whatever reason, it is feasible to use a survival/camping water filter such as this water filter to filter this water and make it safe for drinking.
If you’d like more information about building a rain water collection system, the folks over at Old World Garden Farms have built a great system and they have written an article about how it was put together and how it works. Check it out below.
For emergency drinking water storage, check out: WaterBOB WB-06-001 Emergency Drinking Water Storage it fits in your bathtub and holds 100 gallons of water.
(Photo from: Old World Garden Farms)