What is grey water?

Grey water is the term water damage restoration professionals use for Category 2 water, a contaminated water source that poses health risks but contains fewer pathogens than black water. Common sources include overflows from washing machines and dishwashers, leaking water heater tanks, discharge from bathroom fixtures, and backed-up toilet waste (before significant bacterial growth). It sits between clean water (Category 1, such as burst supply lines) and black water (Category 3, which contains sewage and is highly toxic).

The distinction matters because grey water requires different containment, extraction, and decontamination methods than other water types. It may carry bacteria, detergents, and other household chemicals that can cause illness if ingested or absorbed through cuts or mucous membranes. A washing machine overflow or dishwasher leak that seeps into drywall, flooring, or personal belongings will need to be treated as contaminated material rather than simply dried out.

In Ontario restoration work, identifying whether intrusion water is grey, clean, or black determines the scope of remediation needed. If your home has experienced an appliance overflow or similar grey water event, professional restoration services can properly assess contamination levels, remove affected materials safely, and apply appropriate disinfection protocols.