Seeing as rain is a natural occurrence, it would seem strange to some that capturing and then saving that rainwater would be illegal.
That being said, in some states, while it is not illegal to capture and save rainwater to care for animals or to water plants or crops, it is restricted when it comes to using that saved rainwater for human consumption.
For years people have debated if diet coke is better or worse than a regular coke and it seems like no one can reach a verdict on this debate and everyone holds a different opinion and preference.