Waste water from kitchen sinks is considered blackwater unless

Blackwater is wastewater that contains fecal matter and pathogens, such as from toilets. Greywater is wastewater that is less contaminated, such as from showers, sinks, and washing machines1. However, the classification of kitchen sink wastewater may vary depending on local codes and regulations. Some states and authorities consider kitchen sink wastewater as blackwater because it may contain food waste and germs123. Others consider it as greywater if it meets certain quality standards and is used for beneficial purposes, such as irrigation or toilet flushing45. A CIR (Credit Interpretation Request) is a process to seek clarification on a specific credit or prerequisite in a LEED rating system, but it does not change the definition of blackwater or greywater.

Greywater Reuse | WaterSense | US EPA4

Greywater - California Department of Water Resources5

What Is Greywater? What Is Blackwater? | HomeServe USA1

Grey Water / Reclaimed Water | University of Maryland Extension2

What is meant by the terms Gray water and black water3

Credit Interpretation Requests (CIRs) | U.S. Green Building Council