Building Management Hawaii August/September - (Page 34)

Safeguarding Your Building's Water What you can do to reduce the risk of contamination By Mike Cunningham boileRs & backflow W hen we turn on our faucets for a drink of water, to wash fruits and vegetables or to shower, we take it for granted that the water is safe. Our municipal water suppliers expend vast amounts of time, energy and resources to ensure delivery of clean, good tasting and safe water. This potable water is delivered to our homes and businesses under pressure through a pipeline network that connects to all system users. There are two types of hazards that are of concern when it comes to our water supply: pollution and contamination. A pollutant is any substance that affects the color or odor of the water, but does not pose a health hazard. A contaminant can cause illness or death when ingested. While the likelihood of contamination from a crossconnected source is low, pollutants or contaminants can be introduced to a pressurized water supply system by backflow from a connected water user. Any contamination could have serious wide-ranging health and safety concerns. Backflow can be described as "the undesirable reversal of the flow of water or mixtures of water and other undesirable substances from any source (such as used water, industrial fluids, gases or any substance other than the intended potable water) into the distribution pipes of the potable water system." Backflow can occur either by back siphonage or backpressure. Back siphonage occurs when higher-pressure fluids, gases or suspended solids move to an area of lower pressure fluids. A good example of this is when you use a straw to drink a beverage. Suction makes the pressure of fluid inside the straw lower, causing liquid to move from the cup inside the straw and up into your mouth. This is also an example of an indirect crossconnection, in which undesirable material is being pulled into the system. Here's another way to imagine this scenario: One end of your garden hose is attached to your home's water system, and the other end is placed down into a bucket of herbicide. Suddenly, an abrupt loss of water occurs in the main water line serving your home (such as a water main break or large volumes of water released from a fire hydrant). What would happen is that the pressure drop would cause a reverse flow in the water line-and in a system with no backflow prevention, insecticide from the bucket would be sucked 34 August-September 2014 BMH into your drinking water and potentially into the main water line serving your community. An example of backpressure would be if air is blown through the straw and bubbles emerge from the submerged end. If, instead of air, natural gas or contaminated fluid had been forced into a potable water tank or line, it could be carried to your kitchen faucet. This would be an example of a direct cross-connection in which undesirable material is being pushed into the system. Backpressure can force an undesirable contaminant to enter potable water piping. Sources of backpressure may be pumps in the water distribution system, boilers, heat exchanging equipment or power-washing equipment. In these cases there may be an almost constant risk of overcoming the static water pressure in the piping. To reduce the risk of contamination, a backflow preventer assembly can be installed on your water line. A backflow preventer is a mechanical valve that stops the reverse flow of potentially contaminated fluids into a potable water system during conditions of back siphonage or backpressure. This device is installed near the property lines where a user connects to the municipal water lines. Typically it looks like a pipe that comes out of the ground, turns 90 degrees to a backflow preventer assembly and then turns 90 degrees back into the ground. Your water purveyor may conduct annual testing to ensure that all backflow preventers are working properly to provide protection to all users of a community's water system. Only trained certified testers are allowed to conduct a testing procedure, and results should be submitted to the water system. Stay in touch with your mechanical systems maintenance and repair contractor to make sure certified testing on your backflow preventer is performed regularly. A properly functioning backflow preventer will help protect your building occupants from the dangers of water contamination and pollution. Mike Cunninham is the founder, CEO and president of Doonwood Engineering, Inc., a mechanical contractor specializing in backflow preventers, boilers and heaters, compressors, fans, heat pumps, pumps, storage tanks and valves. The company has served Hawaii and the Pacific Region for 39 years. Visit www.doonwoodengineering.com. www.buildingmanagementhawaii.com http://www.doonwoodengineering.com http://www.buildingmanagementhawaii.com

Table of Contents for the Digital Edition of Building Management Hawaii August/September

Roofing Warranties: Read Them
Heeding Pacific Cyclone Warnings
Eco-friendly Metal Roofing
Cool Roofing Technology
When Good Pipes Go Bad
Why Cast Iron Pipes Fail
Is Your Sewer Squeaky Clean?
Water Heaters Versus Boilers
Preventing Backflow
Safeguarding Your Building’s Water
Safeguarding Your Building’s Water
Why Regular HVAC Inspections Matter
Why Regular HVAC Inspections Matter
Industry News
Industry News
On Site: A Well-Run Association
On Site: A Well-Run Association

Building Management Hawaii August/September

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