Water-use reduction is a good opportunity for all projects to earn points. If you’re familiar with this credit from earlier versions of LEED, though, keep in mind that it’s gotten harder. LEED 2009 introduced WEp1: Water Use Reduction as a prerequisite, calling for a 20% reduction for all projects. In contrast with NC-v2.2 WEc3, which used to award one point for a 20% reduction, the points for 2009 now start with a 30% reduction with for two points, and go up to four points for a 40% reduction.
The baseline for measuring water savings has also become more demanding. The LEED 2009 baseline for commercial lavatory faucets is 0.5 gallons per minute (gpm), whereas the previous baseline was 2.5 gpm.
It’s still very doable
Even with these more stringent requirements, both the credit and the prerequisite should still be fairly easy to achieve with careful fixture selection. You also have the option of replacing potable water with non-potable sources—for example using captured rainwater, or reusing lavatory water, to flush toilets.
Since you will already be designing fixtures to meet the 20% prerequisite, it is not much of a stretch to meet the 30% threshold to start earning points under this credit.
Solutions are simple and widely available
If you pay close attention to the flow rates of the water fixtures you select (gallons per minute for flow fixtures and gallons per flush for flush fixtures), you should be able to achieve a 30% reduction in water use by using widely available efficient fixtures—at a minimal cost premium and without compromising comfort.
Some typical approaches here include low-flow faucets with sensors, low-flush or dual-flush toilets, and low-flush or waterless urinals. Use of graywater and rainwater for toilet flushing is also a fairly common way to contribute to the credit.
Combining several of these strategies can bring your water savings within the 30%–40% range, maxing out your points for this credit. A 45% reduction makes you eligible for an exemplary performance point under IDc1.
Take note: both WEp1 and this credit address interior water use only, but certain strategies that apply to this credit—like graywater reuse—can also be applied to outdoor water use reduction. It is also important to understand that the prerequisite and credit only cover water closets, urinal, lavatory faucets, showers, kitchen sink faucets and pre-rinse spray valves. Other water using appliances and irrigation are not included.
Try it—you’ll like it
When water-efficient fixtures first appeared in the 1990s, they often didn’t perform very well, creating a lot of doubts that still may be harbored by some project team members. Research and development as well as new testing protocols have really changed things since then, so make sure these doubts are put to rest. Providing hands-on experience with efficient fixtures by visiting another LEED building is a good way to do this.
Follow these key steps
- Set goals for interior water-use reduction.
- Determine full time equivalent (FTE) occupancy and fixture usage groups.
- Determine the baseline water use budget for indoor water use.
- Choose fixtures and water reduction or reuse strategies.
- Estimate the project’s water usage by creating a design case water use budget.
- Use the LEED Online form to compare baseline and design-case water budgets to determine the water reduction percentage for the project.
- Complete the LEED Online credit form.
Consider these questions when approaching this credit
- What occupancy patterns are expected?
- What are the highest-intensity water uses? How can you target these for savings?
- Is rainwater collection feasible on your site? What are potential sources of graywater for your project? Does the municipality or local water utility supply reused water through a purple pipe?
- Are rebates or incentives for water-efficient fixtures available in your area?