Here's a great tip from Stephen and Rebekah Hren from their book The Carbon-Free Home: 36 Remodeling Projects to Help Kick the Fossil-Fuel Habit. Harvested rainwater needs filtration before it is potable. Pollution, particles from the air, debris from the collection system (your gutters) are not things you want to find in your tall glass of ice water. Instead of investing in a garage-sized Brita pitcher, Stephen and Rebekah have another idea: sand.
Harvest Rainwater With This DIY Purifier