Drawn to a life of eco-crime? Gray water recycling offers lots of opportunities. Gray water is water that has been employed for household use. Reuse of gray water is illegal in many states because of the potential to contaminate groundwater with bacteria, but many folks do it. The most common offense? Re-routing your clothes washer to drain outside and water the plants. That's illegal in most states. Don't want to go to jail for conserving water? There are high-tech residential systems that filter gray water to remove sediment and pathogens. For now, they're quite expensive and tightly regulated by the government.