Exam EDGE-Expert Topic 1 Question 75 Discussion

Within the CBCI EDGE curriculum, greywater is defined as relatively low-contamination wastewater generated from bathing and handwashing activities, typically coming from fixtures such as showers, wash basins, and bathtubs. This type of wastewater is considered suitable for recovery and reuse in certain non- potable applications, depending on local codes and the treatment approach, because it does not contain toilet waste.
A water closet WC produces blackwater, not greywater. Blackwater contains fecal matter and urine and therefore has a much higher pathogen load and organic content. Because of this, it requires more stringent treatment processes and different health and safety controls compared with greywater systems. In EDGE water measures, greywater reuse calculations and strategies are based on sources like showers and hand basins, while toilet discharge is excluded from greywater source assumptions.
Therefore, among the listed fixtures, the one that does not produce greywater in EDGE is the water closet WC, making option D the correct answer.