The IICRC S500 standard sorts water losses by contamination. Category 1 is clean water from a sanitary source, a supply line or a faucet. Category 2, grey water, is significantly contaminated: washing machine discharge, dishwasher overflow, toilet water with urine. Category 3, black water, is the serious one. Sewage, river flooding, or any water that sat long enough to grow bacteria.
The category decides the whole plan. What gets dried and saved, what gets cut out and disposed of, what protection the crew wears, how the space gets sanitized. And categories degrade: clean water left sitting for days becomes a Category 2 or 3 problem. Nonstop Restoration classifies every loss on arrival and treats unknown water as contaminated until proven otherwise, because guessing wrong on this one puts your family’s health on the line.