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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 if there is significant changes in water pressure. A backflow condition can result in water contamination if hazardous cross-connections exist, regardless of all treatment processes.

What are cross-connections?

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

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 back-pressure into EMWD’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.

While single-family residences are not generally required to have a backflow device, you can help prevent backflow contamination in the following ways:

  • DO NOT leave hoses attached or submerged in unsafe water such as fertilizer or cleaning solution.
  • Confirm that anti-siphon type irrigation valves are installed on irrigation valves.
  • Install a hose bib vacuum breaker. Please note that most new homes are already equipped with anti-siphon faucets.

Backflow related inquiries, concerns and/or Test Maintenance Reports can be emailed to