@ Alchemy- Since you brought up the subject of sustainable design, I thought I should add a bit about whole house water systems that also separate gray water from wastewater, and catch or recycle this water. The gray water is then filtered through a specialized filtration system. After filtration, the water is pumped underneath lawns, landscaping, and flowerbeds to irrigate plants and lawns.
A well-designed gray water system will save water, replenish the water table, and be completely safe. Gray water is naturally fertilized because the potassium and other fertilizing minerals are not filtered by the system. Instead, they are fed directly to the plants. You just have to be careful to use soap products that are biodegradable and safe for gray water systems.