Here's a sci-fi solution for an age-old problem that leaves 1.1 billion people without access to clean water: Beam ultrasound waves into polluted water, blowing up the cellular walls and carbon bonds of contaminants. What's left is a cool drink of fresh H2O. Ultrasound waves have already been used to break up sewage in sanitation systems. Now that the probes that produce the sound waves are getting more powerful, however, scientists are retooling the devices to decontaminate large tanks of water, a process called sonolysis. Portable sonolysis machines could be deployed to isolated villages in developing countries. In urban areas, sonolysis could treat water tainted with industrial pollution. (See the full story.)