Gray water is defined as the wastewater generated from various indoor and outdoor household activities, excluding water that comes from toilets (which is classified as black water). This includes wastewater from sinks, showers, bathtubs, washing machines, and sometimes dishwashers.
To clarify further:
- Indoor Household Usage: This includes water from activities such as bathing, cooking, washing dishes, and laundry.
- Outdoor Household Usage: This might involve water from irrigation, washing cars, or outdoor cleaning, but typically gray water systems are more focused on indoor sources.
- Surfactants: Gray water can contain surfactants (soap and cleaning agents), but it is generally defined irrespective of surfactant presence—what makes it gray water is its source rather than its chemical composition. However, certain treatment systems or guidelines may specify limitations on specific contaminants, including surfactants.
In summary, gray water is typically all household wastewater from various non-toilet sources, and it can be reused for purposes such as irrigation or flushing toilets, depending on local regulations and treatment practices.