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Back-pressure is when a pump, elevated tank, boiler, etc. in a private system creates pressure that is greater than the pressure provided by the city water system. This can reverse the direction of flow, pushing contaminates into the drinking water system.
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A cross-connection is any temporary or permanent connection between the potable (e.g., drinking) water system and another source containing non-potable water or other substances that could contaminate your drinking water if a backflow condition occurs.
An example of a temporary connection could be a garden hose attached to a sink or a spigot with the end of the hose submerged in a tub full of detergent. An example of a permanent connection could be the water supply line to the boiler of a hot water heating system.
If you have any questions or concerns regarding cross connections or backflow prevention devices, please call the Utilities Department at 707-431-3369.
There are a couple of easy ways you can prevent a cross-connection:
Backflow is just what it sounds like: water flowing in the opposite direction from its normal flow. With the direction of flow reversed (due to changes in pressure), backflow can allow contaminants to enter the potable water system through cross-connections. Without proper backflow devices, something as useful as your garden hose has the potential to contaminate your home’s water supply and the public water system.
A potentially hazardous cross-connection occurs every time someone uses a garden hose sprayer to apply fertilizer or herbicides to their lawn. Without a backflow prevention device between your hose and the spigot, the contents of the hose and anything it is connected to can backflow into the home’s water system and contaminate your drinking water.
Backflow can occur 2 different ways, by back-pressure or back-siphonage.
Back-siphonage occurs when there is a sudden reduction in the water pressure in the distribution system, such as if a water main breaks or if the Fire Department uses a large amount of water to fight a fire. When this occurs water flow can be reversed. This can create a suction effect, drawing contaminates into the drinking water system.
Backflow into the public water system can introduce contaminates, making the water in the system unusable or unsafe to drink. Every water supplier has a responsibility to provide water that is usable and safe to drink under all foreseeable circumstances.
Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink. For these reasons, each water supplier must take reasonable precautions to protect its public water system against backflow.
The City of Healdsburg recognizes 3 methods of backflow prevention:
The method of backflow prevention required is based on the degree of hazard that the property and the various uses within the property represent to the city water supply. For more information, download a table showing the required backflow assembly for typical applications.
Recycled water and rainwater should not be placed in storage containers that are connected to piped landscape irrigation systems or to a drinking water supply. Recycled water and rainwater storage containers may only be connected by hose to separate irrigation systems (i.e., hoses connected to above ground drip irrigation systems or sprinklers that are disconnected from potable water supply). Additionally, all equipment (hoses, etc.) and storage containers that come into contact with recycled water or rainwater should be dedicated for use only with non-potable water.
For instances where different systems (potable, rainwater, or recycled water) could come into contact with each other or where any parts of the system are underground, these must be inspected by the City and verified to have an air-gap separation to prevent cross-connection to the drinking water supply. These systems may be subject to backflow device requirements of the City’s cross-connection control program.
A backflow prevention assembly is an approved, testable assembly which uses spring loaded valves to prevent potential contaminates from backflowing into the city water system.
Backflow Prevention Assembly
Backflow Prevention Assembly with Green Freeze Protection Cover
It is the responsibility of the water customer to ensure that the backflow prevention assembly is in proper operating condition at all times. Backflow prevention assemblies must be tested annually. The City of Healdsburg sends notices to customers reminding them when the annual test is due.
The customer must contact a City of Healdsburg recognized tester to perform the test. If any repair work (including repairs resulting from freeze damage) or maintenance is performed on the assembly, a city recognized tester must re-test the assembly immediately and submit the test results to the City.
To be considered for the City's recognized tester list download and turn in the completed application form from our Cross Connection Control Program Page.