Question 1

What is the baseline fixture flush/flow rate referenced for the LEED Water Efficiency prerequisite?

Accepted Answer

LEED's water efficiency credits typically use the Energy Policy Act (EPAct) 1992 and 2005 as the baseline fixture performance standard. Projects must show percentage reductions compared to this baseline. Fixtures performing better than baseline earn points.

Question 2

Which type of water use is addressed by the LEED Outdoor Water Use Reduction prerequisite?

Accepted Answer

The LEED Outdoor Water Use Reduction prerequisite specifically addresses landscape irrigation. Projects must demonstrate strategies to reduce or eliminate potable water use for irrigation through plant selection (native/adaptive plants), efficient irrigation systems, or non-potable water sources.

Question 3

What is greywater?

Accepted Answer

Greywater is wastewater from non-toilet fixtures (sinks, showers, bathtubs, laundry) that contains relatively low levels of contamination. In LEED, greywater can be reused for non-potable applications (toilet flushing, irrigation) to reduce potable water demand.

Question 4

What flow rate (GPF) does a WaterSense-labeled dual-flush toilet use for a full flush?

Accepted Answer

WaterSense-labeled toilets must use no more than 1.28 gallons per flush (GPF) for a full flush — 20% less than the 1.6 GPF EPAct standard. Dual-flush toilets use 1.28 GPF (full) and 0.8 GPF (reduced). These rates are important for LEED water efficiency calculations.

Question 5

Which LEED credit rewards projects for metering water use to support conservation?

Accepted Answer

The Water Metering credit in LEED rewards projects for installing water meters that track a minimum number of subsystems (irrigation, indoor plumbing, reclaimed water, etc.). Metering enables ongoing monitoring, early leak detection, and data-driven conservation.

Question 6

LEED WE credits for outdoor water use reduction can be earned by:

Accepted Answer

LEED WE Outdoor Water Use Reduction rewards using native/adaptive plants, efficient irrigation technology, and reduced turf areas to achieve 30–50% or more irrigation water reduction versus a baseline of conventional landscaping. Eliminating all landscaping can also qualify.

Question 7

Which plumbing fixture type can help earn LEED WE indoor water use credits?

Accepted Answer

LEED WE Indoor Water Use Reduction rewards fixtures with flow rates lower than the baseline (determined by LEED's fixture performance tables based on EPAct 1992). Water-efficient toilets, urinals, faucets, and showerheads — particularly those meeting EPA WaterSense criteria — earn points.

Question 8

Graywater reuse in LEED supports which Water Efficiency credit?

Accepted Answer

Graywater (lightly contaminated water from sinks, showers, and laundry) can be treated and reused for non-potable applications like toilet and urinal flushing. This reduces demand for potable water and earns LEED WE credits for indoor water use reduction.

Question 9

LEED requires building-level water metering as a prerequisite. The primary purpose of this metering requirement is to:

Accepted Answer

LEED's Water Metering prerequisite requires a permanent water meter monitoring whole-building water consumption. The meter data is used to detect leaks, track actual vs. projected performance, and support LEED's ongoing performance goals. Five years of data must be shared with USGBC/GBCI.

Question 10

Cooling tower water efficiency LEED credits address which environmental concern?

Accepted Answer

Cooling towers lose water through evaporation, blowdown, and drift. LEED's Cooling Tower Water Use credit rewards increasing cycles of concentration (less blowdown) through water treatment optimization, reducing the potable water makeup rate — cooling towers are major water consumers in commercial buildings.

Water Efficiency Practice Questions

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