Aquaduct Bike Purifies Water As You Pedal
Mike writes "Winner of the '08 Innovate or Die competition sponsored by Google and Specialized, the Aquaduct is a pedal-powered concept vehicle that transports, filters, and stores water. The design has massive implications for communities where safe and secure sources of drinking water are not readily accessible."
Some of the areas of the world with the worst water quality are very high-humidity, where you may sweat even if you're riding at 20 mph.
And as far as "not pushing yourself hard enough," in most of the world, a bicycle is primarily transportation, not exercise.