Categories: how dirty the water is
The IICRC S500 standard sorts water damage into three categories by contamination. The category decides what can be dried and kept and what has to be removed.
| Category | Also called | Typical sources |
|---|---|---|
| Category 1 | Clean water | Supply line, faucet, ice maker line, rainwater that hasn't touched soil |
| Category 2 | Gray water | Washing machine or dishwasher discharge, toilet overflow with urine but no feces, aquarium leaks |
| Category 3 | Black water | Sewage, floodwater from outside, storm surge, any water that sat long enough to grow bacteria |
Classes: how much has to be dried
Class describes how much water was absorbed and how hard the drying job is, which sets how much equipment the crew uses.
- Class 1: small area, little absorption, mostly low-porosity materials
- Class 2: a whole room, with carpet and the lower part of walls wet
- Class 3: water came from above; ceilings, walls, insulation and carpet are saturated
- Class 4: specialty drying for hardwood, plaster, concrete or stone that hold water deeply
Why this matters to you
When a company tells you carpet pad has to go or drywall has to be cut, the category is usually why. Ask them which category and class they've assigned and to note it in their paperwork; insurers use the same terms.