Quote Originally Posted by Prodaytrader
Rain water didn't do anything more then not cause more problems for you. Water is not a magic element in that a certain kind is more magical then another kind. High quality water is not an improvement to plants, it's a requirement of plants. The plant assumes that it's water source will be pure and clean, it does not assume it's water source will be bad and contaminated.
That seems like a really narrow view. If you thing rainwater is just H and O think again. I would say dust, volcanic activity or many variables could make your rainwater really tasty to your plants. If it works go for it.

I would like to see someone do a test with two similar clones and see if it actually has any benefits over tap water.