Backflow is the undesirable reversal of flow of non-potable water or other substances through a cross-connection and into the piping of a public water system or consumer's potable water system. There are two types of backflow: backpressure backflow and backsiphonage.
Backpressure backflow is backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer's potable water system. Backpressure (i.e., downstream pressure that is greater than the potable water supply pressure) can result from an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both. Increases in downstream pressure can be created by pumps, temperature increases in boilers, etc. Reductions in potable water supply pressure occur whenever the amount of water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains.
Backsiphonage is backflow caused by a negative pressure (i.e., a vacuum ~ or partial vacuum) in a Public water system or consumer's potable water system. The effect is similar to drinking water through a straw. Backsiphonage can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.
Source: The American Backflow Prevention Association - http://www.abpa.org
Tap water providers and bottled water providers must meet the same water quality standards. In fact, tap water providers are required to conduct more frequent water quality testing and reporting than bottled water providers. Some consumers prefer the taste of bottled water, and some choose bottled water because they have special health needs. But tap water is a much better deal at costs of 1,000 times less than bottled water.
We conduct regular water system flushing to remove any mineral build-up and sediment from the pipes and also to ensure that water circulates adequately throughout the system. Fire hydrants may also be opened to conduct fire-flow capability tests.
Homes with unheated basements or crawl spaces may be at risk for freezing water lines or for bursting of internal plumbing lines. By following the actions below, you can minimize the risk of freezing or bursting pipes in your home.
- Insulate your water pipes in unheated areas by wrapping with pipe insulation or blankets.
- Disconnect and drain garden hoses.
- Cut off water to exterior faucets and open faucets to drain pipes, or install exterior faucets that cut water supply off inside foundation walls.
- Areas with exposed pipes should be heated or kept warm.
- Open a tap and let the water run in a steady stream. Drip both hot and cold water at faucets in kitchen and bathrooms. This keeps water moving through the pipes, as well as relieves built-up water pressure in the pipes if they should freeze. Set single lever faucets in the center so both hot and cold lines drip. Pay particular attention to pipes running in outside walls.
- Open cabinet doors under sinks in the kitchen and bath if the cabinets are located on exterior walls, to allow inside heat to pipes.
The amount of money invested in these precautions will be a fraction of the cost of repairing damaged lines.