What is "grey" water?

"Grey" water refers to wastewater that is generated from domestic activities such as washing dishes, laundry, and bathing, which can be treated and reused for non-potable purposes, such as irrigation or toilet flushing. This type of water typically has less contamination compared to black water, which comes from toilets and contains sewage. Since grey water can be recycled and used for practical purposes, this makes it an environmentally sustainable option for water management, especially in areas facing water scarcity.

In contrast, water from industrial processes generally would not qualify as grey water, as it may contain harmful chemicals and contaminants not suitable for reuse in household applications. Rainwater collected for irrigation, while it may be a sustainable practice, is technically not classified as grey water. Similarly, water runoff from agricultural activities often carries pesticides and organic matter, thus being classified as contaminated rather than suitable for non-potable reuse.