Indoor water use reduction

Intent

To reduce indoor water consumption.

Requirements

Building Water Use

For the fixtures and fittings listed in Table 1, as applicable to the project scope, reduce aggregate water consumption by 20% from the baseline. Base calculations on the volumes and flow rates shown in Table 1.

All newly installed toilets, urinals, private lavatory faucets, and showerheads that are eligible for labeling must be WaterSense labeled (or a local equivalent for projects outside the U.S.).

Projects where fixtures or fixture fittings are not within the tenant spaces are exempt from this prerequisite.

Table 1. Baseline water consumption of fixtures and fittings

Appliance and process water use

Install appliances, equipment, and processes within the project scope that meet the requirements listed in the tables below .

Table 2. Standards for appliances

Table 3. Standards for processes

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: