The flooding conditions from Hurricane Michael inspire a revisit of backflow prevention; an unseen technology that assures a safe drinking water supply by keeping water running in one direction by maintaining pressure differences. Analogous to the way we want electrical current to run in one direction, failure of backflow prevention technology poses a near-instantaneous health risk for the contamination of potable water supplies with foul water. In the most obvious case, a toilet flush cistern and its water supply must be isolated from the toilet bowl. In a less obvious case, but at greater scale, a damaged backflow prevention technology at a university research building can contaminate an host-community potable water supply.
As dangerous as the failure of backflow technology may seem; its application, operations and maintenance can be overdone; notably by manufacturers, compliance and labor interests. As we explain elsewhere on this blog, safety in one technology can be so overdone, that it poses a risk to other elements in campus infrastructure. Facility managers are effectively risk managers because they must continually triage their operations and maintenance obligations.
We will drill down into more details on the consensus documents that establish standard of care for a backflow prevention operation and maintenance program during our teleconference on October 12th, 11 AM. Anyone is welcomed to join with the login credentials at the upper right of our home page.
The American Water Works Association is one of the first names in ANSI accredited non-profit trade associations that develop backflow prevention consensus documents that are referenced in local and state building codes; and also in education facility design guidelines and construction specifications. There are other ANSI accredited standards developers in the backflow prevention technology space — the IAPMO Group and ASSE International — for example. We will cover them independently as their documents evolve; holding forth on the safety and sustainability perspective of the user-interest in the education facilities industry.
In 2013 the original University of Michigan codes and standards advocacy enterprise began advocating the user-interest at the local, state and national level because, like most large research universities it had a complicated interdependency with the host city water supply system within which its own was nested; made even more complicated by a large hospital and research enterprises where scientific materials presented elevated risk to the potable water users on the perimeter community.
Two standards, which are referenced deep in state building codes, were given scrutiny by internal experts with a balanced view of the competing requirements of safety and economy:
AWWA C510-17 Double Check Valve Backflow Prevention Assembly. This standard describes the double check-valve backflow prevention assembly for potable water applications. The purpose of this standard is to provide the minimum requirements for double check-valve backflow prevention assemblies for potable water applications,including materials, general and detailed design, workmanship, and shipping and delivery.
AWWA C511-07 Reduced-Pressure Principle Backflow Prevention Assembly. This standard describes the reduced-pressure principle backflow prevention assembly. A complete [RPZ] assembly consists of a mechanical, independently operating, hydraulically dependent relief valve located between two independently operating, internally loaded check valves that are located between two tightly closing resilient-seated shutoff valves with four properly placed resilient-seated test cocks
Its proposals sought performance specifications for, a) backflow lubricants (so that the units were less likely to break during maintenance operations) and and require replacement during maintenance, b) clarification about where reduced pressure zone (RPZ) valves are required.
Since the July 2016 organization (see ABOUT) AWWA has revised both standards; one of which — AWWA C511 — seems to have responded to our proposal for clarification about where RPZ’s are required. We will continue following these documents specifically, and the AWWA, IAPMO and ASSE suite generally. The AWWA standards landing page is linked below:
All standards developing technical committees welcome data-driven proposals at any point in their revision cycle. Our next water safety standards teleconference is scheduled for October 12th, 11 AM. Use the login credentials at the upper right of our home page.
Category: Water Safety, Plumbing, Mechanical
Colleagues: Mike Anthony, Richard Robben, Steve Snyder, Larry Spielvogel