Backflow: The Reverse
Flow of Water
Have you heard the plumbing terms "backflow" or "anti-siphon"? Both of these terms are important to your health. Backflow is the reverse flow of water in the water supply system in your home, and it's caused by back pressure, back-siphonage or a cross-connection.
Back pressure is a condition that occurs when something, such as when a boiler for a hot water heating system malfunctions and sends water backwards into the fresh water supply.
A cross-connection is an unprotected connection between a potable water system and any source or system containing unapproved water or a substance that is not or cannot be approved as safe, wholesome, and potable.
Back-siphonage is due to a vacuum or partial vacuum being created in the water supply. Here's one extreme example of back-siphonage. If you drop the garden hose into your kid's wading to fill it, and while the hose is under water and running, the fire department begins to pump water nearby, the pressure in your water supply system can drop so much that the water in the wading pool can be sucked back into the water supply. The next time you get a drink at your kitchen faucet, you could be drinking water that your kids had been playing in just a short time before.
Even worse, if you were spraying garden chemicals with one of those hose-end sprayers, when you water supply system lost pressure, you could have you glass of water flavored with bug killer.
Backflow preventers are available; you may have one on an outdoor faucet. Clothes washers have a builtin device that prevents water in the machine from flowing backwards, and many community plumbing codes require check valves on outdoor water faucets, anti-siphon ballcocks in toilet tanks and air-gaps in the drain line of dishwashers.
So, remember when it's up to you to install or replace such things as ballcocks always select the one labeled "anti-siphon". And don't ever remove a back-flow devise.
The American Backflow Prevention Association (ABPA) is an organization whose members have a common interest in protecting drinking water from contamination through cross-connections. ABPA is an organization dedicated to education and technical assistance. Through its network of regions and chapters, local needs and interests are supported with the resources of the national organization. ABPA is committed to advancing all aspects of backflow prevention for the continued protection of all water users.
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