Water Category Deterioration Over Time (IICRC S500)
Applies the S500 principle that water category is determined at the time of remediation, not by the source alone: origin category, elapsed wet time, a warm-environment flag, and contaminant contact return the likely current category. A clean loss left standing or warm reclassifies upward; contaminant contact escalates toward Category 3. When in doubt the higher category is assumed; the restorer and S500 govern.
Formula and source
Reference lookup with threshold comparisons: origin category + elapsed wet hours + warm flag + contaminant-contact flag -> likely current category. Contaminant contact -> Category 3; Category 1 past ~48-72 h (sooner if warm) -> Category 2; otherwise origin.
Category-at-time-of-remediation principle, by name; ANSI/IICRC S500.
Audience
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