Every water loss we encounter gets assigned a Category. This is the first step in assuring that remediation efforts follow standard industry guidelines.
There are three basic "categories" or types of water damage as defined by the IICRC in the ANSI Standard S-500 document. The basic differences between them have to do with the source of the water and how long it has been affecting the materials in question. Readers interested in the details should consult the source document. The following is meant only as a basic guide:
Category 1: Potable water source. Examples: frozen / broken supply pipes, garden hose spigot, water heater leak, appliance supply line leak (washing machine, dishwasher, ice maker, etc.). Under ideal circumstances, carpet, pad, and other materials can all be restored. After 72 hours, a Category 1 loss is treated as Category 2.
Category 2: Non-known-pathogen-containing source ("gray water") source. Examples: sink drain lines, washing machine or dishwasher discharge, sump pump (non-sanitary) backup, toilet water before the trap. Under ideal circumstances, carpet and other materials can be restored. Carpet pad should be removed. After 24 hours, a Category 2 loss is treated as Category 3.
Category 3: Known-pathogen-containing source ("black water") source. Examples: sewage backup (from beyond trap), ground water, river, or ocean flooding, In a Category 3 loss, all affected porous materials should be removed. Affected carpet, pad, drywall, upholstery, bedding, draperies, etc., should all be replaced.