Include any low-flow or waterless fixtures, water reuse systems, or onsite wastewater treatment systems in your construction and design development documentation.
Determine how treated wastewater will be used onsite. It must either be reused, such as for toilet flushing or irrigation, or must be infiltrated onsite.
Verify that your onsite wastewater treatment system is capable of treating the wastewater to tertiary standards. State governments determine exactly what constitutes “tertiary treatment” based on allowable remaining levels of certain nutrients and organisms. Your civil engineer will need to be in charge of this determination.
Determine what type of onsite wastewater treatment is most appropriate for your project. Typical septic-tank-and-leachfield systems used in many rural areas where there are no sewer systems do not treat water to tertiary standards so they can’t be used to earn this credit.
Even if you are attempting Option 2, you will want to select water-efficient fixtures, which minimize the quantity of wastewater treated onsite. To accomplish this, target the most consumptive fixtures to achieve the greatest water reduction, but keep in mind the very different maintenance requirements for waterless fixtures. See WEp1 and WEc3: Water Use Reduction for more information. Also, review the Option 1 steps of this credit.
Compare the baseline and design case water budgets to determine the water reduction percentage for your project. The LEED Online credit form has a built-in calculator to facilitate this calculation. Repeat this process until selection of water fixtures and strategies is finalized and your project’s water reduction goals have been met.
If needed, size graywater and rainwater systems to satisfy the credit requirements. Sizing these systems can be more complicated than you might initially think. It’s best to involve a civil engineer or someone familiar with these systems.
Track and record information on applicable fixtures, including the manufacturer, model number, and flush or flow rate. This will help you when filling out the LEED Online credit forms. Fill out the LEED Online form early in design simply as a draft to determine if you are meeting the requirement.