Section P2906 addresses greywater systems that recycle water from sinks, showers, and washing machines for non-potable uses. Greywater cannot contain fecal matter (must come from white goods, not toilets). Greywater is stored in tanks and treated before reuse. Separate piping systems must be used for greywater (typically purple color coding) to prevent contamination of potable water supply. Backflow prevention is critical to prevent greywater from entering drinking water lines. Water quality treatment may include filtration, ultraviolet sterilization, or chlorination.