I mentioned water powered lighting regarding the project going on in Ireland a few days ago, but it’s nothing like this! Sylvania has produced (and is selling) a water-powered LED fixture for the shower that indicates water temperature. It attaches to the shower spout, and water flowing through the unit powers it. When the water is 78° or below, it indicates blue – and above 105° indicates with red.
Check out the Sylvania LED Ecolight Water Powered Shower Light, Amazon is selling it.