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Water Damage Categories 1, 2 and 3 Explained
Updated · Copperline editorial · 2 min read
Category 1 — clean water
Water from a broken supply line, faucet or water heater. Materials can often be dried in place if drying starts quickly.
Category 2 — gray water
Water with some contamination: washing-machine or dishwasher overflow, toilet overflow with urine but no feces, aquarium water. Cleaning and antimicrobial treatment are added.
Category 3 — black water
Sewage, toilet overflow with feces, and floodwater from outside. Porous materials it touched — carpet, pad, drywall — are removed, and everything is cleaned and disinfected. See sewage backup cleanup.
Water gets worse with time
Clean water left standing for a couple of days can degrade to Category 2 or 3 as it picks up contaminants and bacteria grow. Fast extraction keeps cleanup simpler.
Categories versus classes
Category describes how contaminated the water is (1 clean, 2 gray, 3 grossly contaminated). Class, a separate scale in the IICRC S500 standard, describes how much evaporation is needed based on how much material got wet and how porous it is. Both shape the drying plan: a Category 3 loss means removing porous materials, while a high-class loss means more equipment and time.
Call a professional if
- Wastewater coming up a tub, shower or floor drain
- Toilets gurgling or backing up when other fixtures drain
- Sewage odor in the house
- Wet flooring near a bathroom with no clean-water source
Water Damage Categories 1, 2 and 3 Explained: follow-up questions
Can clean water become Category 3?
Yes. Clean water that sits for days or contacts contaminated materials can degrade to Category 2 or 3.
Is a dishwasher leak Category 1 or 2?
Dishwasher and washing machine discharge is usually treated as Category 2 (gray water) because it contains detergents and food or organic matter.
Every home differs; editorial standards.