How to make "pico-hydroelectric" power - doesn't require a lot of water and generates enough power for at least one household. I was thinking something like this in-line with your water inlet system since it is already under pressure.
The ultimate lightweight backpacking camp light. A tiny 4 gram chip sits atop a regular alkaline battery which acts as body, handle, stand and power source. Two modes: high hours) and low hours). High mode produces about as much light as a