Discover the important distinctions between graywater and blackwater in the context of LEED certification. Learn which wastewater sources are considered graywater vs blackwater.
Table of Contents
Question
Which describes the difference between graywater and blackwater?
A. Graywater includes storm water and potable water, whereas blackwater Includes stormwater and Irrigation
B. Graywater may be used for irrigation or drinking, but blackwater should only be used as a source of process water
C. Graywater includes wastewater from lavatory faucets, whereas blackwater includes waste water from toilets and urinals
D. Graywater is approved for human consumption and may be supplied from wells or municipal water systems, whereas blackwater is comprised of wastewater from toilets and urinals
Answer
C. Graywater includes wastewater from lavatory faucets, whereas blackwater includes waste water from toilets and urinals
Explanation
Graywater includes wastewater from lavatory faucets, whereas blackwater includes wastewater from toilets and urinals. This describes the difference between graywater and blackwater according to LEED. Graywater is wastewater that has been used for non-potable purposes, such as washing hands or dishes, but does not contain human or animal waste.
Blackwater is wastewater that has been contaminated with human or animal waste from toilets or urinals. Graywater can be reused for certain purposes after minimal treatment, such as irrigation or toilet flushing, whereas blackwater requires more advanced treatment before reuse or disposal. The LEED Green Associate Candidate Handbook states that one of the strategies for achieving waterefficiency is to “use non-potable water (graywater) for sewage conveyance”.
Graywater refers to wastewater from non-sewage sources like bathroom sinks, showers, bathtubs, and washing machines. This wastewater contains minimal amounts of contaminants and pathogens compared to toilet wastewater. Graywater can potentially be reused for non-potable purposes like landscape irrigation or toilet flushing with proper treatment.
In contrast, blackwater is wastewater from toilets and urinals that contains fecal matter and urine. Blackwater has much higher levels of pathogens, organic matter, and other contaminants. It requires more intensive treatment before reuse or discharge.
Stormwater and potable/drinking water are separate categories from graywater and blackwater. Stormwater is runoff from precipitation, while potable water is treated to drinking water standards. Graywater should not be used for human consumption even with treatment.
In summary, the key difference is that graywater comes from lavatory sinks and appliances and has lower contaminant levels, while blackwater comes from toilets/urinals and is much more contaminated. Understanding this distinction is important for implementing water efficiency and reuse strategies in LEED projects.
USGBC LEED Green Associate certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the USGBC LEED Green Associate exam and earn USGBC LEED Green Associate certification.