If you like sour and the water is not rancid is there any danger in drinking the water? If so what is the danger? I grew up drinking it and it was delightful. There were never any warnings against drinking it. If the water is unsafe to drink then in my opinion the coconut meat is also unsafe. Please be specific.
The only thing I know is that sour water from the brown mature coconuts is horrible tasting but I didn't get sick from it. I would not keep the meat if the coconut water is in question. The meat is not safe from bacteria if bacteria has touched it.
Check out what organyx has to say here about the pink and purple color: http://www.chow.com/food-news/84067/is-coconut-water-bad-for-you/
I've found this site very informative in the past: http://foodbabe.com/2014/07/15/how-to-buy-the-healthiest-coconut-water-and-avoid-the-worst/