Categories describe water contamination: Category 1 is clean, Category 2 is gray and Category 3 is black water such as sewage or floodwater. Classes describe how much water and how fast it will evaporate, from Class 1 to Class 4.
Category 1: clean water
Water from a clean source such as a supply line. It can become Category 2 or 3 if it sits or contacts contaminants.
Category 2: gray water
Water with significant contamination, such as washing machine or dishwasher discharge. It can cause illness if consumed.
Category 3: black water
Grossly contaminated water such as sewage, rising floodwater or water from outside. Porous materials that it touches are usually removed. See sewage backup cleanup and flood damage cleanup.
Classes 1 to 4
Class 1 has minimal water absorption, Class 2 affects a whole room with wet carpet and wall wicking, Class 3 comes from overhead and saturates ceilings, walls and insulation, and Class 4 involves deeply held water in low porosity materials like hardwood and concrete.
Why it matters
Category and class decide the cleanup steps, safety gear and drying plan. Use water damage restoration in Houston to be connected with companies that follow these standards.
Frequently asked questions
Can clean water become black water?
Yes if it sits long enough or touches contaminants.
Who sets these standards?
The IICRC S500 standard.
Sources and further reading
- IICRC: Institute of Inspection, Cleaning and Restoration Certification
- EPA: Mold Cleanup in Your Home
Related services
Sewage Backup Cleanup
Safe cleanup of sewer backups, drain overflows and contaminated water.
Learn more
Flood Damage Cleanup
Cleanup, removal and drying after rising water enters a Houston property.
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Biohazard Cleanup
Safe cleanup of blood, bodily fluids, trauma scenes and contaminated spaces.
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Water Damage After a Fire
Drying and cleanup after hoses and sprinklers soak a burned building.
Learn moreGeneral information, not legal, insurance or engineering advice. Water Damage Restoration Houston does not perform the work.