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ICC News Release
For Immediate Release
October 14, 2015
Contact: Steve Daggers
1-888-ICC-SAFE (422-7233),

Plumbing Efficiency Research Coalition Releases Drainline Transport Report

ICC is Among Coalition Members Providing New Insight into Building Drains

The Plumbing Efficiency Research Coalition (PERC) released Phase 2 of the long-anticipated study The Drainline Transport of Solid Waste in Buildings. The Phase 2 report is now available on the PERC website. The study builds on the findings of the Phase 1 report of the same title and provides new and important insights into the performance of building drains as water flows are incrementally reduced as a result of water-efficiency-related regulations.

“As technology continues to change, the principle reasons we need plumbing codes remain the same—to protect the health of a building’s occupants and the surrounding community, and to protect property from damage by water or sewage,” said Lee Clifton, Director of PMG Resources for the International Code Council (ICC).

PERC identified drainline transport as its first research project when it was formed in 2009 to develop research projects that support the development of water efficiency and sustainable plumbing products, systems, and practices. PERC’s six member organizations are represented by Clifton of ICC; Mary Ann Dickinson, Alliance for Water Efficiency; Billy Smith, American Society of Plumbing Engineers, Peter DeMarco, International Association of Plumbing and Mechanical Officials; Gerry Kennedy, Plumbing-Heating-Cooling Contractors National Association; and Barbara C. Higgens, Plumbing Manufacturers International.

The PERC Phase 2 report addresses several important areas of study that were not included in the Phase 1 effort. Importantly, the study evaluates the potential for a sanitary pipe size reduction to improve drainline transport characteristics and help to facilitate further flow reductions in plumbing fixtures. Like the Phase 1 report, the study applies to commercial building drains as they present the greatest risk for chronic blockages resulting from water flow reductions.

The PERC Phase 1 study was both informative and influential. In 2013, the U.S. EPA cited the report’s findings that high efficiency toilets (HETs) flushing at a maximum of 1.28 gallons per flush provided satisfactory drainline transport as justification to move forward with a WaterSense specification for commercial HETs and flushometer-valves.

PERC plans to publish a supplemental report, PERC Phase 2.1, in early 2016. The supplemental report will provide a preliminary investigation on the impact of dual flush toilet discharges and slope deviations on drainline transport efficacy.


About the International Code Council

The International Code Council is a member-focused association. It is dedicated to developing model codes and standards used in the design, build and compliance process to construct safe, sustainable, affordable and resilient structures. Most U.S. communities and many global markets choose the International Codes.