Water categories: what the industry standard says and what to ask

Chosen when: Where did the water come from: A sewer or drain backup, or a toilet overflow

IICRC's S500 consensus body describes Category 3 water as grossly contaminated and able to contain pathogenic, toxigenic or other harmful agents, and its examples include sewage and wasteline backflows beyond any trap. Treat it as a different job from clean water: stay out, stop using water, and expect the crew to remove porous material that sewage soaked. Ask the company to write down the category and the protective steps it will take.

Sewage cleanup · Water categories and classes explained: what the public record says

Chosen when: Where did the water come from: Floodwater or storm runoff from outside

MDHHS says floodwater can contain bacteria and raw sewage, so treat it as contaminated until a company has inspected it. The S500 body says weather-related water is not automatically Category 3 and that the category follows from inspection, so ask what the company inspected and what it concluded. Your flood or homeowners coverage is a separate question: see the will insurance pay tool.

Flooded basement · Water categories and classes explained: what the public record says

Chosen when: Where did the water come from: Rain through the roof or windows, or wind-driven rain

The group that maintains the S500 says top-down water ingress, wind-driven rain and other weather-related water are not automatically considered Category 3, and that the category is set by inspection. If a company says all storm water is Category 3, ask what it found. Dry the area within 24 to 48 hours, as EPA advises, to prevent mold growth.

Storm damage · Water categories and classes explained: what the public record says

Chosen when: Where did the water come from: A washing machine, dishwasher or similar

Trade shorthand calls appliance drain water Category 2. We have not verified that label, because the full Category 1 and 2 definitions are in the paid S500, which we have not read. Ask the company which category it recorded and on what basis, and if it will recheck it as the water sits. EPA says to dry water-damaged areas within 24 to 48 hours.

Water damage · Water categories and classes explained: what the public record says

Chosen when: Any other answers

Trade shorthand calls fresh supply-line water Category 1. We have not verified that label against the paid S500 definitions, which we have not read, so treat it as a question to ask. Whatever the label, do not leave it sitting. EPA says to dry water-damaged areas and items within 24 to 48 hours to prevent mold growth, and to throw away materials that soak up water and cannot be cleaned and dried.

Burst pipe cleanup · Water categories and classes explained: what the public record says

Chosen when: Where did the water come from: A broken supply line or fixture; How long has it been wet: Longer, or I do not know · or · Where did the water come from: A broken supply line or fixture; How long has it been wet: One to a few days

The longer water sits, the more a company should reassess what it is dealing with, and you should ask if it did. We do not give a time at which a category changes, because the public IICRC pages do not state one. What EPA says is that mold can grow on wood, drywall, carpet and furniture left wet for more than 24 hours after a flood, so call now and ask for moisture readings at the first visit.

Structural drying · How long does water damage take to dry? The 24 to 48 hour window and the drying log

Chosen when: Where did the water come from: I do not know

Say so on the call. The S500 body says the category is set by inspection, so a company should look rather than guess. Until then, stay out of standing water and away from wet electrical equipment, and treat anything that smells like sewage as Category 3. Photograph the water line first.

Emergency water removal · Water categories and classes explained: what the public record says