Arlington Rolls Out New Engineering Backflow Preventer Details

This article has been re-published with permission from The City of Arlington, TX. About the authors: Joe Gildersleeve is Water Resources Services Manager for City of Arlington Water Utilities. Randy Holland is Assistant Managing Director of EnviroDesign Management and a Best Practices Consultant for Safe-T-Cover Enclosures.

When a developer decides to build anything from a sidewalk to a storm water catchment system, standard details exist to show them the way a city wants the work to be done. These engineering guidelines protect residents from unsafe practices that could damage property or affect quality of life.
Arlington, a North Texas city of about 380,000 residents, expanded the reach of its standard details in 2016 to include the installation of backflow preventer assemblies immediately following the water meter. We hope the success of those changes, and the motivations behind them, can be of value to other utilities.

Backflow assemblies are to ensure that no water returns to the public water supply – a concept referred to as premise isolation, containment or point of supply backflow prevention. Some states like New York, New Jersey, California, and Washington are moving towards mandatory premise isolation for commercial and industrial uses. At the federal level however, no such regulations exist.

The American Water Works Association – the voice for water utility operators – addresses this need in its literature. In the preamble to the Cross Connection Control Manual published by the Environmental Protection Agency (EPA), AWWA states, “… The return of any water to the public water system after it has been used for any purpose on the customer’s premises or within the customer’s piping system is unacceptable and opposed by AWWA…”  While this may seem like an all-too-obvious position, it exists because backflow exists and can have dire consequences.

New buildings are not the concern. After all, the local plumbing authority rigorously monitors all new construction projects. A permit to occupy a building is never issued until the building passes inspection. The vast majority of plumbing authorities across the U.S. have adopted one of two plumbing codes: the Unified Plumbing Code, or UPC, or the International Plumbing Code, IPC. Both of these codes have an exemplary record of protecting individual plumbing fixtures from becoming hazards to the on-site users. This point-of-use backflow protection is carefully engaged at all locations where a cross connection might occur, such as water fountains, coffee maker connections, soda dispensers, automatic dishwashers, etc.

But, what goes on after construction can be a mystery. Each day, small business owners like restaurateurs, paint and body shops, auto mechanics, car washes, pet groomers, etc., in the interest of improving some process, make small uninformed changes to their plumbing on their own. Many of these changes, although unintended, create cross-connections with the drain system.

Through a network of licensed inspectors, Arlington monitors testing of 3,000 “high-health hazard” backflow assembly sites, such as healthcare providers and restaurants, each year. Backflow can occur because of high pressures on the premises pushing water back to city-owned water mains(back pressure), or because of unusually low pressures out in the public supply piping pulling water back to city-owned water mains (back syphon).

The city had many motivations for implementing the new details. Some of those included: 

  • Isolation from the inspection process. Because of the volume of plans being reviewed, plumbing inspectors in Arlington’s building department are the primary gatekeepers for acceptable methods. These plumbing inspectors are experienced and knowledgeable, but the guidelines provide them with a clear picture of what backflow methods the city prefers.
  • Unknown changes. Non-conforming and illegal changes to on-site plumbing systems are a big problem for every water provider. TCEQ’s Customer Service Inspection program, mandating a plumbing review of every property that undergoes a material change is helpful, but still is limited to only the properties where changes are announced to the city by application of a building permit or sale. Publicizing these guidelines to commercial users with high health hazard designations is another way to help prevent unknown changes that can be harmful.
  • Subrogation risks. Subrogation is the authority given to insurers to be entitled to a claim for damages on the behalf of its insured when a third party caused a loss. Poor regulation of backflow prevention assemblies can put cities at risk if flooding or other property damage occurs.
  • Local engineers’ survey. A survey conducted by EnviroDesign Management and Safe-T-Cover© over a two-year period became an important factor, as well. This survey of 1,220 DFW civil and plumbing engineers revealed that the local design community was in need of assistance from local water authorities. The results were presented to the city of Arlington in February of 2015 revealing that 3 out of 4 local design engineers stated a need for standard details.

So far, the city and local builders have been pleased with the new guidelines. What makes it so easy is that during the planning process, builders can just write these exact details into the plans. It gets rid of the guesswork and makes a valuable contribution to the safety of our water supply.

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