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Residential Backflow Prevention

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Residential Backflow Prevention Residential Backflow Prevention Most Frequently Asked Questions watts.com Residential Backflow Prevention The combined efforts of cross-connection control (first line of defense) and containment (second line of defense). Most Frequently Asked Questions Q I know that cross-connection control is Q If plumbing codes require backflow protec- important on industrial and commercial tion at the cross-connection, why is a facilities, but is it necessary on residential second line of defense needed? connections? Is there really a risk? ☛ Residential A There are several reasons: The first is that A Cross-connection control is important no plumbing codes, like other rules and regula- Series 8 Hose Vacuum Breaker matter what type of service is involved. should have been installed here. tions, are not always adequately enforced. Industrial cross-connection control programs Pesticides: Chlordane The second, and by far the most compelling have been used for years. Historically, water and Heptachlor reason, is that the day after the certificate of purveyors have recognized the potential risk occupancy is issued, plumbing becomes sub- of health hazard industrial connections in their ject to unauthorized changes. Economic fac- systems and have taken an active roll in pro- tors motivate homeowners to do-it-yourself tecting the public water supply (primary sys- Series 7 Dual Check Valve plumbing. The bottom line is the cost of a tem) from them. The potential risk from resi- backflow preventer should 6" Feed 6" Main competent plumber versus the savings when have been installed here. Water Supply was dential connections has been, for the most (Second Line of Defense) contaminated with pesticide the homeowner does it himself. Generally, the part, overlooked, even though some of the homeowner is not only ignorant of the plumb- most serious cases of backflow originated at ing code requirements, he is totally unaware of a residence. Chlordane was siphoned through the dangers of cross-connection and backflow. a hose at a residence in Roanoke, Virginia, Gate Valve Closed Finally, the installation of a Dual Check Valve contaminating the water supply of an entire backflow preventer at the service connection neighborhood. The cost to the water purveyor divorces the public water supply from the to replace water mains, valves, meters, service domestic water supply and establishes juris- lines, water heaters, ice makers, and other dictional authority and responsibility between plumbing was about $200,000. In addition, the public water supply and domestic water lawsuits totalling several million dollars were system. filed. Since these suits were settled out of Residential - (Second line of defense) Q What types of water system protection are court by the water purveyor and the extermi- Containment at the water meter required in a residence? nator, no records are available on the actual amount paid, but it was probably considerable. Dual Check Valve here A Plumbing codes are very specific here. They (Second line of defense) require backflow protection by cross-connec- Q What do you mean by “second line of To Sill Cock To tion control and many important safety devices defense?” ☛ as follows: A We call this program of containment at the Service 1. Air gaps built into sink, tub, and basin service connection with a Dual Check Valve faucets backflow preventer the “second line of defense” 2. Anti-siphon type ballcocks in water because it is intended as a backup to the closets (toilets) plumbing cross-connection control program Industrial - (Second line of defense) 3. Vacuum breakers on hose bibbs and which controls backflow at the cross-connec- sill cocks tion itself. It might be compared to the safety 4. Backflow preventers or vacuum breakers latch on an automobile door where both would on lawn sprinklers have to fail simultaneously before the door 5. Backflow preventers on supply lines to could open unintentionally. boilers or other equipment containing Q Is the second line of defense concept Boiler non-potable fluids and cross-connected limited to residential systems? ☛ to the potable water system A No, the principle must be applied to all sys- Because some local authorities modify existing tems, although the backup for health hazard national codes, certain areas require backflow facilities would require the use of an assembly protection on the following as well: that was designed for such installations, such 1. Residential swimming pools, hot tubs, as the Reduced Pressure Zone Assembly back- and spas flow preventer. The Dual Check Valve backflow 2. Residential solar heating systems preventer simply was not developed for use in Reduced Pressure Zone 3. Private wells and other auxiliary water Assembly health hazard industrial applications. You supplies wouldn’t put a residential deadbolt on the door Most homeowners do not know they alone to the bank vault, would you? Reduced Pressure Zone are responsible for the safety of domestic Assembly Installed Here. (Second Line of Defense) water system. It is up to the water purveyor Water meter to inform him. Cold water supply from street main Q Is the water purveyor responsible for Q I understand the Dual Check Valve is lim- enforcing the plumbing code? ited by national standards to one-inch size. Double Check Valve A No, but the water purveyor is responsible for Suppose a residence had a service con- ☛ Assembly protecting the public water supply. That nection larger than one inch—what type of responsibility may include taking secondary device would be practical? Series 007 1 measures beyond the plumbing code require- A This would be an unusual situation, but a larg- Sizes ⁄2" – 3" ments, such as installing a backflow preven- er size Double Check Valve Assembly could be tion assembly at residential connections to installed in lieu of the Dual Check Valve. ensure that contaminated water does not enter Q Speaking of national standards, what the distribution system at one point, only to be standards does the dual check meet? served to another consumer down the line. ☛ Series 709 The Dual Check Valve meets the ANSI/ASSE A 1 Generally, the water purveyor’s responsibility Sizes 2 ⁄2" – 10" ends at the service-connection to the consum- Standard 1024. Generally speaking, most er’s water system. However, since the need for standards address the performance and con- this added protection is relatively new (past 15 struction requirements including the quality of years) many premises exist that must be retro- materials and workmanship and the quality of fit or brought up to today’s standard. the bronze, stainless steel, plastic and rubber Therefore, the water purveyor must require the parts, and the spring tension, tolerance and owner to provide proof of compliance with the tightness. current plumbing code and install a contain- Q Do standards ensure reliability? Dual Check Valve ment control device at each service or meter. A No, all water works equipment requires a Backflow Preventer The minimum standard of performance must maintenance program. The more sophisticated No. 7 3 be met before being tied into the system. assemblies, such as the Reduced Pressure Sizes ⁄4" – 1" Q If you are going to install a Dual Check Zone Assembly, the Double Check Valve Valve at the service connection, why not Assembly, and the Pressure Vacuum Breakers go ahead and install a more stringent all have something in common with the Dual device, such as the intermediate atmo- Check Valve. We know that after we test a spheric vent backflow preventer or the sophisticated assembly, a year will generally Reduced Pressure Zone Assembly? go by before we test it again. A If that idea had merit, the water industry During that time, we trust we are protected. would already have adopted it. The fact is, This trust is being hedged, however, with the the industry made repeated requests to back- knowledge that the assembly is manufactured Q Is spot-testing adequate? flow preventer manufacturers to produce a to national standards and will, in all probability, A Selective spot-testing is the mainstay method compact, economical product that could be prevent anyone from getting hurt. The story is of quality control used in every industry in the installed in the meter box as a second line of the same with the Dual Check Valve. The most world today, including the potable water supply defense for the community water system. The significant difference here is that we know the industry. Clearly, spot-testing is nothing new to Dual Check Valve is a direct result of those Dual Check Valve is not installed as a primary the water industry. It is used regularly to test requests. It is the only practical device for device, but as a backup, a sort of insurance meter accuracy, flow rates, and system pres- large-scale residential programs and it is policy against a residence not being or not sure. In fact, spot-testing is used to en-sure designed to be installed with the meter, includ- becoming in full compliance with the plumbing that the water is within the bacterio-logical ing in the meter box, for new or retrofit instal- code. and chemical limits established by EPA. The lations. One could equate the use of a Dual Q You mentioned testing. What are the major Safe Drinking Water Act re-quires that random Check Valve to the installation of a deadbolt on utilities doing about testing the Dual Check samples of water be sent to certified labs. the front door: it provides better protection Valve? Using this method to test Dual Checks Valves than a single lock in the handle, but it certainly A For the most part, they are using selective not only makes good economic sense, it can doesn’t provide the protection of a full-scale spot-testing; but a few are using 100 percent often provide additional valuable information electronic security system—nor does it cost annual testing.
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