WE•Stand For Safe, Reliable Water

A recently published ANSI Standard for plumbing covers a broad range of water efficiency and safety concerns for facilities.

By Facility Executive Staff
From the February 2018 Issue

In November 2017, IAPMO’s Water Efficiency and Sanitation Standard (WE•Stand) was published as an American National Standard, replacing the Green Plumbing and Mechanical Code Supplement (the Green Supplement). The publication of WE•Stand is noteworthy, as it is the first ANSI standard that focuses solely on achieving safe and efficient water use in both non-residential and residential buildings.

water efficiency
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With its last version published in 2015, the Green Supplement is a separate document from the Uniform Plumbing and Mechanical Codes and establishes requirements for green building and water efficiency applicable to plumbing, mechanical, and solar energy (hydronic and photovoltaic) systems. The Green Supplement serves as an adjunct to the Uniform Codes or any of the plumbing and mechanical codes used in the United States.

The supplement is not a “greener” version of the Uniform Codes, but rather, the Green Supplement addresses green building plumbing issues in a number of ways, including:

  • Serves as a repository for provisions that ultimately will be integrated into the Uniform Codes. The Green Supplement is a transitional home for green requirements until they are fully accepted by industry and ready to be included into the code.
  • Serves as a resource for progressive jurisdictions that are implementing green building and water efficiency programs.
  • Is an enforcement aid for existing green ordinances.
  • Is a model for jurisdictions implementing green ordinances.
  • Serves as a resource for inspectors, plumbers, contractors, engineers, and manufacturers in designing, installing, and approving green plumbing and mechanical systems.
  • Coordinates and resolves conflicts among other green building and water efficiency program requirements.

What Is Addressed In We•Stand

The recent publication of WE•Stand is a result of the work of the WE•Stand Technical Committee comprised of 29 industry experts. The provisions contained in the standard reflect the collective experience and knowledge of the committee.

With representation from code officials, manufacturers, plumbing engineers, contractors, the plumbing trades, water efficiency proponents, water utilities, landscape irrigation experts, representatives of other associations, and academia, the contents reflects the latest comprehensive provisions aimed at achieving safe and reliable water efficiencies in and around buildings.

Here is an overview of the provisions contained in the inaugural edition of WE•Stand.

A significant item in WE•Stand is its Water Demand Calculator, an alternative to the industry’s Hunter’s Curve when estimating water supply demand for residential buildings (applicable to single- and multi-family settings). This achievement represents the first practical application of an improved method since the 1940s that does not result in excessive over design and oversizing pipes. The new Water Demand Calculator estimates the supply demand for the whole building, as well as cold and hot water branches and risers for indoor water use based on today’s plumbing fixtures and appliances and usage patterns. The Water Demand Calculator works in conjunction with any commonly accepted rules and procedures for sizing the water supply system.

Use of the calculator in plumbing design aims to: improve scouring action in water pipes, inhibit biofilm growth, reduce water dwell times in premise plumbing systems, improve water quality, speed hot water delivery throughout the plumbing system, and reduce construction costs. It is now available for use with any baseline plumbing code.

Additionally, the following aspects of plumbing systems are addressed.

Provisions for codification and safe use of composting toilets. WE•Stand contains the first set of comprehensive codified requirements for installation, safe use, and maintenance of composting and urine diversion toilet fixtures applicable to commercial and residential applications.

Leak detection systems. New safety provisions for leak detection systems that take fire suppression systems into account.

Landscape irrigation. New efficiency-related provisions for system inspection and performance.

Swimming pool provisions. New requirements pertaining to the energy efficiency of swimming pool pumps per the latest industry standards.

Indoor water efficiency. Contains flow rate and consumption requirements for plumbing fixtures and appliances that take both safety and water and energy efficiency into consideration.

Alternate water sources. Progressive provisions for uses of gray water generated from clothes washers in landscape irrigation.

Allows for the installation of rainwater catchment systems up to 5,000 gallons for non-potable uses without requiring inspections under certain conditions, reducing costs to owners.

Looking ahead, the following are proposed topics for the 2020 version of WE•Stand.

Alternate water sources

  • New requirements for black water treatment and uses.
  • New requirements for stormwater treatment and uses.
  • Safe reuse of commercial kitchen effluent.

Net-zero water and waste

  • Considerations to attain net-zero water and waste performance in buildings.

Commercial foodservice

  • Consideration of new water efficiency provisions for convenience stores.
  • Food waste management (new biological and composting technologies).
  • RO efficiency markers for reject water.


  • Informative appendix on proper installation/maintenance of composting toilets.

Installer qualifications

  • New certification recommendations to help ensure proper installation of water efficient technologies.

Premise water supply systems

  • Efficient arrangement of plumbing fixtures (compact distribution strategies) improves water and energy efficiency and water quality.
  • Investigation into minimum and maximum water flow velocities in premise plumbing.
  • Appropriate uses and maximum length requirement for 3/8″ diameter tubing

Sustainable Drinking Water Treatment

  • New references of industry standards on waste treatment technologies.

Certain material in this article is reprinted from http://www.iapmo.org/WEStand/ with the permission of the International Association of Plumbing and Mechanical Officials. This material and all points or statements using this material have not been reviewed by IAPMO. The opinions expressed herein are not representations of fact from IAPMO.

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