Air Gap Importance

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.

Connection Protection

An air gap is the vertical distance through the atmosphere between the lowest potable water outlet and the highest level of the source of fluid contamination. In other words, it is the point of separation of potable and non-potable piping.

A water treatment system installed with a direct drain connection to a sewer system, a cross connection, has a risk of contamination most anytime. It can happen when a sewer backs up, which is the most common, or when there is a loss of pressure in the system.

One example is a loss of pressure due to a power failure, where a system pump fails to run, that could result in a back siphon causing water flow from the sewage to the house's potable water system. Fire departments have also been known to cause vacuum situations in municipal systems when fighting fires, a situation that can suck water through sewers connected through an illegally cross connected treatment system. This water could contain any number of pathogens that would be introduced into the potable water supply.

Even though every state has some mention of cross connection protection in their plumbing code books, the use of air gap devices in the water conditioning installation is currently on a voluntary basis in many, it seems.

The purchase and use of these devices or the lack of them does not necessarily mean that the water treatment professional isn't using some type of cross connection protection. Cross connection in this case refers to a direct connection, in any building, between a potable water system (fresh water plumbing systems including any connected water treatment devices) and the sewer/waste water system (or, simply put, the drainage system.)

System installers will typically dangle the end of the softener drain line above a floor drain, laundry sink or stand pipe for an open air gap without a device. This can allow over spray and potential water damage. Some construct vacuum break tees out of a tee and a series of fittings, but this method still doesn't allow a plumbing connection with sewer pipe or floor drain, and it's all but impossible to connect vacuum breaker tee to an overhead drain in a basement installation. Some codes allow for an "approved" double check, "check valves" for the purpose of this discussion. This is a mechanical device with springs and / or moving parts. Because of these parts, these devices are likely to fail at some point. Air gaps I've seen have no moving parts and are simply plumbing fittings that are designed or sized to fit in the waste system in a home.

Providing Code Compliance

The use of air gap devices is becoming more popular because it saves the installer time when providing the minimum one inch protection required in most codes. Chances are your state or local code enforcement agency subscribes to such a standardizing organizations as Buidling Officials and Code Administrators (BOCA), Conference of American Building Officials (CABO), Universal Plumbing Code (PC), NSSF International, and the International Association of Plumbing and Mechanical Officials (IAPMO).

Code enforcement varies locally and between states. Most local inspectors don't have the opportunity to inspect installation sites, or installs, because many are either replacement installs or performed after the occupancy permit is granted. A few local inspectors require installers to apply for a permit before installations, which is not only expensive but time consuming. In some cases, occupancy permits are withheld until the air gap is installed.

It's a good idea to get to know your local inspectors. Make them your allies. Find out how they prefer to see air gaps and make sure it agrees with the predominant national plumbing code in your area. The procedure for how drains are to be installed properly is better to come from you, than have them calling you on a suspected illegal cross connection. Generally , health or building departments are understaffed and the people doing the inspections don't have a lot of time to go back for a re-inspection.

Dealers have said......

Before we started our air gap business, I did a phone survey of dealers in my state. I got the phone numbers from local phone books and Indiana Water Quality Association membership directory. The responses were not what I expected. Most knew of air gap devices, but because of a few extra dollars in the cost per installation ($15 to $30), or the fact the inspector overlooks the gaps, or they use floor drains or they stick the drain line into stand pipes or washer drains, dealers didn't use them. Some have said they used subcontractors for installations and didn't feel they were liable. It's still the dealer's name on the equipment. Doesn't it seem they would want to protect the very customers they work so hard to attract and retain?

When sales representatives are in the home, especially if the call is for a replacement unit, they can point out to the customer if the drain is cross connected. The sales person can then report the fact that your installers take the time to upgrade or install proper drains, as a fixed part of the sales presentation. If you point out the fact that the competition doesn't mention the air gap drain, this tells the prospective customer you're concerned about their health and safety and you know your stuff. The marketing value of your professionalism will make yours the system of choice, even if you are a higher priced.

Additionally, the WQA Certified Installer's Home Study Guide includes a section on safe drains; and , even though this section does not specifically mention the use of air gap devices, it clearly shows the use of air gaps in the illustrations and text. Again, many water treatment professionals install air gaps without purchasing manufactured devices; however, devices like these are time savers and professional sales tools for the water conditioning dealer.


The use of a safe drain is covered in the Water Quality Association's Code of Ethics, which states, "Ensure that their products and services are properly applied or installed when they are responsible for such application or installation."

A person may say it's a one in a million chance for backflow contamination due to a cross connection. It is my guess there are over 500,000 water softeners installed every year in this country. Therefore, every other year someone has a problem. This problem, when it occurs, could be on a private well system or municipal system. The media coverage of just such an event has already occurred in Cedar Rapids, Iowa, when a local television investigative reporter discovered a plumbing cross connection directly to a sewer line underneath a manufactured home, installed by a local systems dealer. With this type coverage comes more investigation, and eventual regulation.

We all know we don't need more regulation. Make sure you use a proper air gap. And remember that an air gap device may add to the cost per installation, but also can be an additional marketing tool in your belt, convincing customers of your professionalism and dedication to their safety.

John Harding

Co-Owner of J.H. Verneco Inc