The ALS ice-bucket challenge (which is trying to raise money for a genetically rooted motor-neuron disease affecting less than 1% of the population), has been going viral worldwide for several months. Since you are reading this on the internet right now, I will assume you know what I am talking about and that you, several celebrities you like, or friends of yours have participated. 
Aside from the fact that this challenge has nothing directly to do with ALS, and that ALS research is not really the most logical place to put money if you want to help humanity, it is also a waste of water (duh) and energy (freezing ice costs energy).
In some areas, clean water is more difficult to come by. One such location is the tiny Scottish island of Colonsay, which recently ran out of water and ice cubes after the craze hit the island. Whether they actually ran out, or the system shut off due to excess usage, is unclear. At this point in time, the water has been turned back on and ice can again be bought at the local Tesco.
Aside from on Colonsay, taking part in such a challenge is only advisable if you live somewhere with excess water resources. This means that if you live in California, or any other area where water is less common, you will be doing more harm than good when you do the “ice water challenge.”