If collecting rainwater or reusing graywater, ensure that the key system components, such as water treatment and cisterns, are not removed during value engineering.
Specify signage for water fixtures or strategies that may require special instructions for use, or educate users on water savings. This may include signage for explaining proper operation of dual-flush toilets, waterless urinals, indicating non-potable water if supplied at faucets, and distinguishing pipes carrying reused water for operations and maintenance personnel.
Specify efficient water fixtures in construction documents. Be sure to include specific flow and flush rates (gpm or gpf) for each type of fixture.
Toilet-lid-sink retrofits for standard toilets are one of the most basic and easy graywater reuse tools available, costing around $100. When toilets are flushed, potable water first flows though the sink for handwashing before filing up the toilet tank for flushing.
Many commercial toilets can be retrofitted with dual-flush flushometers, which can cost less than installing new dual-flush toilets. Check with manufacturers for retrofit compatibility.
Flow restrictors and aerators can cost only a few dollars per fixture and can help add efficiency to more conventional sink fixtures. This can also be an easy inexpensive way to retrofit existing faucets; however, make sure restrictors or aerators are compatible with faucet fixtures.
The LEED calculation estimates a standard 15-second use for faucets, so setting the flow duration to a shorter time of 10 seconds interval can help save water and contribute to earning the credit.
Sensors on toilets and faucets are sometimes perceived as saving water. However, several studies have shown that while they may offer some hygiene or other operational benefits, they increase water use substantially, due to “phantom flushes” and faucets running longer than needed as they may interpret the flow of water as a solid object. If you do choose lavatory sensors, look for models with adjustable flow durations, and test the sensitivity of the sensor.
Piping to interior water fixtures is doubled when graywater or rainwater is reused in addition to potable water. This is likely to add upfront costs, but can potentially reduce water and sewer charges.
Untreated rainwater, graywater, and blackwater can corrode plumbing systems, or lead to biological growth. Teams should plan for water treatment, filtration, or using corrosion-resistant materials. The use of seawater for toilet flushing, which is less common, can cause similar problems.