Containment vs. Isolation: The Commercial Backflow Preventer Installation Battle

One of the things we’ve learned about commercial backflow preventer installation over the years is that opinions vary. That’s especially true when you ask a mechanical or civil design engineer, Where should non-residential backflow preventers be located?

Many public water systems are now considering the location and management of assets like meters and backflow preventers more closely. They’re also looking at trends that impact design decision. Direction for the design and backflow prevention systems is based on the requirements of the local public water system. It also has a lot to do with the International Plumbing Code.  

Let’s take a closer look at what causes the divide over the location of backflow preventers. What’s preferred? What are the concerns? And what’s missing?

The Location of Backflow Preventers Causes Concern

If a public water system forgoes their right to require containment backflow prevention at the service connection, the water uses and connections within a water customer’s property must be evaluated frequently. This is done to isolate all potential sources of contamination of the water system.

Public water systems often have limited budgets preventing them from having adequate staff to evaluate potential contamination sources. This is also true of most non-residential water customer budgets. They often resist routine inspections of their water system—even if they’re required. As a result, most municipalities simply require containment protection at the service connection.

But the concerns don’t stop there. Public water systems have numerous other issues to manage, including:

• Access to water system assets like meters, control valves and backflow preventers is currently under scrutiny. Federally-funded state programs like One Call require water systems to mark their service lines on the customer's property up to the meter. In some commercial and industrial properties, the meter is inside a customer’s building or plant.

• Control valves on pressure regulating stations out in the distribution system are vandalized.

• Vaults containing backflow preventers often flood, but are required to be tested by water system staffers annually. This makes what could have been a simple task an arduous.

• When test cocks on backflow preventers become submerged in a vault, bigger problems arise. The protection of the dual check spring-loaded backflow device is lost. The only thing protecting the water line is the test cock ball valve.

When it comes to things like fire sprinkler systems, domestic water systems, and lawn irrigation systems—backflow design ideas may vary. But the obligation of the public water system to protect the water is always the same.

Backflow Prevention Creates Design Concerns

Vague requirements and a lack of communication can create concern among designers when it comes to backflow preventer installation. Licensed civil engineers are usually responsible for designing containment backflow systems outside the building. This includes water, sewer and stormwater systems. But licensed mechanical or plumbing engineer design isolation backflow for water and sewer systems inside the building.

The two typically don’t work together and oftentimes aren’t sure who’s in charge of backflow prevention. Public water system requirements are often vague, so neither knows if they should specify a backflow preventer in their domain. It is even relatively common for the civil engineer to expect the plumbing engineer to be in charge of backflow prevention and vice versa.

Since the regulations and codes are different with every water system, this really comes as no surprise. Things get even hairier when a property is sold or leased to a new tenant. Double check backflow preventers that were previously acceptable now need to be retrofitted to reduced pressure zone (RPZ) devices. Where are those going to be installed? Would the installation of RPZ backflow preventers at new construction be a better solution?

Let’s End the Backflow Preventer Installation Battle

The location of backflow preventers is a critical part of a design plan. It’s a public water system’s responsibility to keep our drinking water safe. That’s hard to do when almost every building needs a backflow preventer. It becomes even tougher when they need to be tested annually. It seems practically impossible for such small agencies to manage.

A simpler solution is to include a backflow enclosure when designing a backflow preventer installation. You can custom design your enclosure with easy access panels to make annual testing a breeze. It’s cost-effective and outside, above ground enclosures are safer, too. For more information, you can download The Guide to Cross Connection Controls and Best Practices and stay on top of the latest trends in backflow preventer installation.