Indoor water use reduction

Intent

To reduce indoor water consumption.

Requirements

Option 1. Calculated water use (2–5 points except Data Centers, 2–4 points Data Centers)

Establishment

None.

Performance

Have fixtures that use less water than the baseline calculated in WE Prerequisite Indoor Water-Use Reduction. Points are awarded according to Table 1.

Table 1. Points for reducing calculated water use beyond the prerequisite level.

Confirm that calculations are up to date. Demonstrate that all purchases made since the end of the performance period meet the design performance requirements.

OR

Option 2. Metered water use (4 points)

Establishment

Meter fixtures and fittings, and record meter data for one year to establish a water-use baseline.

Performance

For projects with at least 80% of fixtures and fittings metered, show a reduction from the baseline year of meter data.

Table 2. Points for reducing metered water use

Behind the intent

Use of potable water – water that has been treated to a quality appropriate for human consumption – in buildings constitutes a large portion of freshwater consumption. Indoor water use in the U.S. is affected by a federal standard for certain plumbing fittings and fixtures, and by the Uniform Plumbing Code (UPC). This prerequisite requires projects to use less potable water than would be allowed by the federal standard and the UPC. Reducing potable water use will result in a number of benefits to the project and to the environment.

• Conserving potable water use reduces the energy and chemicals that must be used to treat water to potable quality.
• Conservation also reduces the energy that must be expended to distribute treated water to consumers.
• Potable water conservation can allow Public Water Systems (PWS) to delay expenditures to expand water treatment capacity.
• Displacing potable water for certain purposes that do not entail human contact or consumption may lead to more sustainable management of community water resources, while decreasing building operating cost.

Strategies to reduce potable water use in buildings will entail the selection of plumbing fittings and fixtures, and water-using equipment that use less water than conventional fittings and fixtures, or the use of alternative water sources. Performance of lower flow fittings, fixtures, and equipment will be an important consideration, because unsatisfactory operation may encourage building owners and occupants to replace conserving devices with higher flow units.

Step by step guidance

Common steps

The calculation to support this prerequisite compares a design case to a baseline case.

1. Be certain to select WaterSense Fittings and Fixtures for those units that are subject to WaterSense labeling.
2. The calculation for this prerequisite is: