Purple is the standard color of pipe adopted by the international utility industry to distribute treated reclaimed water—a highly treated and regulated commodity that is monitored and inspected by state- and locally certified environmental and health agencies.
The International Association of Plumbing and Mechanical Officials (IAPMO) publishes the Uniform Plumbing Code (UPC) every 3 years, with the 2009 edition now available. The code's 2006 edition required yellow pipe with black lettering for onsite alternate water—any water that is not potable, including graywater, harvested rainwater, stormwater, and air conditioning condensate. However, the 2009 edition changed the code to require purple pipe for all onsite alternate water, as well as treated reclaimed water.
IAPMO
The primary objective of the UPC is to protect the potable water supply. From the IAPMO perspective, there are only two types of water: potable and non-potable. Implementing the use of purple pipe for all non-potable water is intended to prevent cross connection between the two. In addition, gas industry engineers are concerned that a yellow alternate water pipe could be confused with a natural gas pipe, which is also yellow.
Reclaimed Water Utilities
Reclaimed water utilities know that all non-potable water is not the same. These utilities have spent 3 decades and extensive resources building trust and educating the public about reclaimed water, which is consistently of a much higher quality than untreated or minimally treated onsite water. Municipally treated and distributed reclaimed water is used to augment groundwater and surface water supplies; augment streams and wetlands; provide industrial process water and cooling waters; provide landscape and agricultural irrigation; and for various construction purposes.
Potential cross connections between two purple pipe systems containing significantly different quality water could expose the public to inadequately treated water and create a public health concern. In addition, public confidence in the municipal reclaimed water system could be seriously compromised if public exposure and cross connections occur.
Industry Reaction
The Water Environment Federation, American Water Works Association, and WateReuse Association joined to write a letter in opposition of the revised IAPMO code. This letter was the first to be endorsed by three organizations in a common effort to eliminate a public threat. Based on the letter, IAPMO formed a task group to review the code requirements and to develop alternative codes acceptable to both plumbing code inspectors and municipal utility providers.
Collaboration between all affected parties will be necessary to develop the right solution. Every sector—including designers, installers, owners, building officials, and regulators—has needs that must be addressed. The IAPMO task force is currently in the process of writing a supplement to the UPC revision that will create a more elaborate pipe-coding system. It is scheduled for completion by fall 2009.