Water categories
- Water
- Mold
- Biohazard
Professional requiredThis page explains the work. It does not tell you how to do it, because doing it without training and equipment is unsafe.
Water is graded Category 1 clean, Category 2 significantly contaminated, and Category 3 grossly contaminated. The category describes what is in the water rather than how much there is, and it decides whether porous material is dried in place or removed and discarded.
- Category 1 — Clean water — Most materials can be dried in place if drying starts quickly and is documented to a moisture goal.
- Category 2 — Significantly contaminated water — Porous materials frequently come out rather than being dried in place. This is where scope, and cost, diverge sharply from a Category 1 loss.
- Category 3 — Grossly contaminated water — Porous materials that contacted Category 3 water are generally removed and discarded. Drying is not a substitute for removal, and this is the single most expensive determination in a water loss.
Why this needs a professional
Determining the category is not visual and is not a homeowner call. Category 2 and 3 water require containment, protective equipment and frequently removal rather than drying.
Sources
Every source cited on this page
- T2ANSI/IICRC S500 — IICRC (accessed 2026-08-22)
- T1A Brief Guide to Mold, Moisture and Your Home — US EPA (accessed 2026-08-22)
- T1About Mold and Health — CDC (accessed 2026-08-22)
Guidance that does not name a water category, a smoke type, or the peril and whether the water was internal or external is not specific enough to act on. This page names them.