Water damage is graded by how contaminated the water is, using three categories set by industry standards. Category 1 is clean water from a broken supply line, a burst pipe, or an overflowing sink with no soap or waste. Category 2, sometimes called gray water, carries some contamination from sources like a washing machine or dishwasher discharge.
Category 3, often called black water, is grossly unsanitary and can contain sewage, ground surface flood water, or bacteria that cause serious illness. Porous materials soaked by Category 3 water, such as carpet and drywall, usually must be removed rather than dried. You can look up these terms and grading details in our glossary.