No. 5

Although totally frivolous, no one can say that having bright blue water pour from the tap wouldn't be cool. The actual device is the small cylinder attached to the faucet, which housed the blue LED. I don't know of it only works when the water is on, but if there is a button on the thing, it would make for one interesting night light.

Source - http://www.thinkgeek.com/homeoffice/gear/8122/