Backflow & Cross-Connection Prevention

EMWD works diligently to deliver safe and reliable drinking water to its customers. This effort begins with protecting our water supply sources – such as groundwater wells – and continues through the entire treatment and distribution process until the water reaches the meter. However, some hazardous conditions may exist on customer properties which risk that safe drinking water supply.

Water systems are designed to have higher pressure than a customer’s system to keep water flowing in the right direction. However, when there is a drop in water main pressure, a reverse flow – or backflow – can occur. This can be caused by incidents such as water main breaks or high demands such as fire fighting. A backflow condition can result in water contamination if hazardous cross-connections exist, regardless of all treatment processes.

Learn more:

• What are cross-connections?
• What does a backflow device do?
• Theft prevention

What are cross-connections?

Whenever a plumbing fixture is connected to the drinking water supply, a potential cross-connection exists. Some examples include:

• Hose bibs
• Hose attachments to apply weed killer or fertilizer or to flush antifreeze
• Irrigation or lawn sprinkling systems
• Swimming pools and spas
• Ornamental fountains
• Fire sprinkler systems
• Solar heat systems
• Wash basins and service sinks
• Auxiliary water supplies (wells, storage tanks, and second feeds)

If the water on your property is in contact with a harmful substance – such as fertilizer – and that water  backflows into the main water system, it could cause illness or, in extreme cases, death.

To prevent these risks, EMWD requires backflow prevention devices where mandated by law and works with customers to educate and eliminate potential hazardous cross-connections.

What does a backflow device do?

Backflow devices are required by State law where fire or irrigation services are installed. The device prevents back siphonage and backpressure into the District's main water supply, protecting the water supply from cross contamination.

Most multi-family, commercial, and industrial properties as well as properties with an auxiliary water supply and properties with irrigation meters in EMWD’s service area are required to have a backflow device, specifically a Reduced Pressure Assembly backflow device.

All installed devices must be tested on an annual basis. Each year, customers will receive a reminder notice along with a certified list of testers. Failure to have the device tested could result in the termination of service. Click here for the certified list of installers/inspectors.

While single-family residences are not generally required to have a backflow device, you can help prevent backflow contamination by…

• not leaving hoses attached or submerged in unsafe water such as fertilizer or cleaning solution.

• confirming that anti-siphon type irrigation valves are installed on irrigation valves.

• installing a hose bib vacuum breaker. Please note: most new homes are already equipped with anti-siphon faucets.

Theft Prevention

Due to the scrap value of the bronze used in backflow devices, EMWD has experienced an increase in thefts of these devices.

You can help prevent thefts by:

• painting the device. Paint acts as a deterrent since painted metal is less valuable.

• camouflaging the device. Fake rocks work well to hide backflow devices. Just be sure to keep a one-foot clearance around the device.

• installing a device with less metal. There are some approved models that utilize plastic, making them less valuable to thieves.

• enclosing the device in a locking enclosure. Keep in mind that backflow devices must be tested annually and the tester will need access to your device during that time.

Examples of secure backflow devices: