Current Air Gap Rules Keep the Regulators Away
"This article first appeared in the March 1999 issue of Water Conditioning & Purification Magazine. It is reprinted here by permission of WC&P's publisher, Publicom Inc. of Tucson, Arizona, U.S.A. Any reproduction of this article, in whole or in part, must be with permission of Publicom Inc."
The Importance of Proper Installation
Summary: One of the important components of a proper water conditioning installation is provision for safe drainage by avoiding a possible "cross connection," or any point where a water supply pipe or container is joined directly to a sewer pipe. It's at this point that an installation has even a remote chance of introducing danger to a household in a backflow situation. This risk can be drastically reduced, if not eliminated, by using a sufficient "air gap" system as described here.
In the late 1930s and early 1940s, a sectional committee on minimum requirements for standardization of plumbing equipment realized the need for protection of the purity of a potable water supply in building pipelines. A technical subcommittee on air gap use and backflow preventers was organized. After a number of reports and revisions, a draft was submitted to over one hundred health supervisory officials, plumbing inspectors, state plumbing associations and others involved in the Industry.
Once additional recommendations, changes and refinements were complete, a final draft was adopted. The final draft was forwarded to American Standard and was designated an American Standard in January 1942. At the time, this standard dealt with water closets, fountains, sinks, open tanks, vats and manufacturing. Water conditioning was still in its infancy then, and I doubt anyone knew what was coming in terms of advances in the industry. In 1991, the standard was revised to comply with more current technology and is again under review.