The three categories of water damage are Category 1 (clean water from a clean source like a supply line), Category 2 (gray water with some contamination like from a washing machine), and Category 3 (black water, heavily contaminated like sewage). The category determines the cleanup method, safety requirements, and what materials can be saved.
What you need to know
Category 1 is clean, Category 2 is gray, Category 3 is black/sewage. The category drives cleanup and safety.
In detail
Category 1 — Clean Water: This is water from a clean source, such as a broken supply line, a leaking faucet, or rainwater entering through a roof. It poses no significant health risk initially, but if left sitting, it can degrade into Category 2.
Category 2 — Gray Water: This water has some contamination. Sources include washing machine overflows, dishwasher leaks, or water that has sat long enough to begin degrading. It may contain chemicals or microorganisms and requires more careful handling.
Category 3 — Black Water: This is heavily contaminated water, including sewage, groundwater, river water, and water from a sewer backup. It contains bacteria, viruses, and pathogens. Category 3 water requires protective equipment, containment, and often removal of porous materials. DIY cleanup is dangerous and should not be attempted.
Factors that affect the answer
- Source of the water
- How long the water has been sitting
- Whether contaminants are present
Safety
Category 3 water is a health hazard. Avoid contact and do not attempt DIY cleanup. If there is immediate danger to health or safety, call 911.
Related service
This answer relates to our Sewage Backup Cleanup page.
Sewage Backup CleanupRelated questions
Last reviewed: September 2026