Rainwater collection is an excellent way to secure a sustainable water source. I've got a simple gravity-fed system in my place. I use a 55-gallon food-grade drum placed atop a sturdy platform. The rainwater from the roof gets funneled into this drum through a decent-sized downspout. Remember to install a good screen filter at the top to keep debris and bugs out. You'll want to make sure there's an overflow port too, in case of heavy rain.
Cleaning the collected water is crucial. I usually boil the water before use, but another good way is using bleach: a scant 1/8 teaspoon per gallon should do the trick. Just remember to let it sit for 30 minutes before use.
One thing to bear in mind, if you live in a dry climate, you'll likely need a bigger catchment surface for those scant rains. Do you have any specific concerns about your local climate impacting your rainwater collection plans?
