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

The WE•Stand Technical Committee (TC): The on-time publication of WE•Stand is a result of the excellent work of the dedicated WE•Stand TC. Comprised of 29 leading industry experts, the provisions contained in the standard reflect the centuries of 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 contained in the 2017 WE•Stand contains the latest comprehensive provisions aimed at achieving safe and reliable water efficiencies in and around buildings. IAPMO sincerely appreciates the efforts of the WE•Stand TC!

What’s in it? See below for just a few of the significant new provisions contained in the inaugural edition of WE•Stand:

New Water Demand Calculator
: Big news! WE-Stand provides a new alternative to Hunter’s Curve when estimating water supply demand for residential buildings! 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 method is applicable for both single- and multi-family dwellings. A complimentary, easy-to-use 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. This results in: improved scouring action in water pipes, inhibiting biofilm growth; shorter water dwell times in premise plumbing systems, improving water quality; faster hot water delivery times throughout the plumbing system, saving energy, water and money; and reduced construction costs. Is this a big deal? You bet it is. Plumbing systems designed utilizing the new method will deliver water and energy efficiencies for the entire life of the plumbing system, at a reduced cost! It is now available for use with any baseline plumbing code.

New Provisions for the Codification and Safe Use of Composting Toilets: WE•Stand contains the first set of comprehensive codified requirements for the installation, safe use and maintenance of composting and urine diversion toilet fixtures applicable to commercial and residential applications.

New Safety Requirements for 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 thoughtful 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. New requirements that reduce the cost of retrofitting gray water systems in single family homes. Allows for the installation of rainwater catchment systems up to 5000 gallons for non-potable uses without requiring inspections under certain conditions, reducing costs to owners

If water efficiency is important to your community, please look into the 2017 IAPMO WE•Stand for the latest provisions for attaining safe levels of efficiency in the built environment.

Help IAPMO make WE•Stand even better! Get involved and be part of the leading effort to advance water efficiency and sanitation!

Here’s what we have teed up for 2020 WE•Stand:

Alternate Water Sources

  • New requirements for black water treatment and uses
  • New requirements for stormwater treatment and uses
  • The safe reuse of commercial kitchen effluent

Net-Zero Water and Waste

  • Considerations for safely attaining net-zero water and waste performance in buildings

Commercial Food Service

  • Consideration of new water efficiency provisions for convenience stores (e.g., Slurpee machines)
  • Food waste management – new biological and composting technologies
  • RO efficiency markers for reject water


  • Informative appendix on the proper installation and maintenance of composting toilets

Installer Qualifications

  • New certification recommendations – helps 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 addressing water treatment technologies