atula asks:What is rain water harvesting?

This can be done, and in its most basic form (a rain barrel) you just have a barrel that is outside that you allow to fill up with water when it rains. This water can be used for watering plants but should not be given to animals or humsns without filtering. In colorado, which is where I live, rainwater collecting is illegal. This is because so much water goes to other places from Colorado that preventing it from running off into streams is considered depriving them of their water rights.