Gray water includes wastewater from showers, bathtubs, bathroom sinks, laundry tubs and washing machines, but not from toilets, kitchen sinks or dishwashers. The latter sources typically have high bacterial content, making them unsuitable for irrigation. Gray water comprises 50 - 80% of residential wastewater. California regulators have recently loosened the requirements for using gray water for certain irrigation purposes by issuing an emergency decision that allows residents to create simple water-reuse systems without a construction permit. View more information about California's new standards for gray-water systems (PDF).