August 1, 2007 Up the Creek

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Backflow Prevention

            From Article 12, Colorado Primary Drinking Water Regulations:


“A public water system...shall have no uncontrolled cross-connections to a pipe, fixture, or supply, any of which contain water not meeting all applicable provisions of the Colorado Primary Drinking Water Regulations.”

            This short paragraph places the responsibility for the safety of the water everywhere in the public system squarely on the public system. The public system is considered to extend up to a line of demarcation between public and private that is drawn right after the water meter. USCDWUA owns and maintains the water meter and meter pit. Everything after that is a private system under the control of somebody else, for example the homeowner. You might not think of your home plumbing as a “system,” but it is in fact a simple or complicated arrangement of pipes and fixtures with water going to places and doing things that we don’t know about.

            Since your private system is not operated by USCDWUA, we can’t verify that the water in it meets all the applicable provisions of the regulations. There are countless ways that unsafe water can be present in your home system, from defective toilets to improperly installed irrigation systems. None would present a threat to the public supply, unless the water can flow back into the public lines. So, our responsibility under Article 12 is to make sure our connection to it is not “uncontrolled,” which is legalese for “no backflow prevention.”

            The short summary of the above is that we are installing dual check valve devices in all meter pits that don’t already have them. For many years, dual check valve assemblies have been a standard feature of the meter yokes we use. So, while many meter installations are already protected, those installed in the early days of the system are not. Those old meters don’t actually have a meter yoke, but are an assembly of pipes screwed together on the spot to accommodate a meter, and, in most cases, a pressure regulator.

            Unfortunately, there is not enough room in a meter pit to comfortably house a meter with backflow prevention and a pressure regulator. Since about 1970, USCDWUA has not allowed pressure regulators to be in the meter pit. The old installations with regulators have remained “grandfathered,” but this will no longer be possible when the new yokes with dual check valves are installed. You will need to make arrangements to have your pressure regulator installed in the house, or in a pit separate from the meter pit.

            Another side effect of backflow prevention is the need to have an expansion tank included in your plumbing system. With a backflow preventer and leak-free plumbing, there is no way for water to expand when heated by your water heater. The expanding water may be forced out through faucets, or the pressure relief valve on your water heater. An expansion tank is a small tank, about a gallon in size, that has compressed air separated from the water by a sealed diaphragm. Heated water is thus allowed to expand safely.

            You will be notified when your meter is scheduled to be updated. The older meter pits will have to be dug up by USCDWUA and completely replaced. Some meters installed with a yoke, but no backflow device, can be fixed without being dug up. Our goal is to be 100% in compliance with Article 12 within five years, at the latest.                                                                                                                 dh

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