Water categories: how contaminated the water is
The category describes the level of contamination in the water. It is not a fixed label, and water can become more contaminated the longer it sits in a building.
- Category 1 (clean water): water from a sanitary source, such as a supply line or a fixture overflow that has not yet contacted contaminants. It can degrade into a more contaminated category over time.
- Category 2 (gray water): water with significant contamination that could cause discomfort or illness if contacted, such as overflow from a dishwasher or washing machine.
- Category 3 (black water): grossly contaminated water, which includes sewage and floodwater from outside the home. Materials exposed to it generally need more careful handling.
Water classes: how much moisture is present
The class describes how much water the building has absorbed and how difficult it will be to dry. Classes are assessed by the provider using moisture readings and the types of materials involved.
- Class 1: a small amount of water affecting limited materials, with low absorption, such as a spill on a concrete floor.
- Class 2: a larger area of absorbent material, such as carpet and pad across a room, with moisture in the walls up to a moderate height.
- Class 3: water that saturated ceilings, walls and insulation, often from above, requiring the most air movement.
- Class 4: water that has absorbed into materials that are difficult to dry, such as hardwood, plaster, masonry or concrete, which requires specialty drying methods.
Why the category matters for your home
A higher category usually means more cautious handling, more protective equipment for workers and more material that may need to be removed. A clean-water loss in a bathroom may allow more materials to be dried in place, while a sewage backup may require removal of porous materials such as carpet and drywall.
Ask your provider to explain the category and class in writing, and to tell you which materials they expect to save and which they expect to remove.
Questions to ask a provider
You do not need to become an expert, but a few questions help you understand the plan.
- What category and class do you assign to this water, and why?
- Which materials can be dried in place, and which need removal?
- Could the category change while the water sits, and how will that be handled?