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Las Vegas Valley Water District employee performing work on backflow prevention device.

Preventing backflow

The Water District works with its customers to protect the drinking water supply from pollution and contamination caused by cross-connections and backflow.

What is backflow?

Backflow occurs when water that has already entered a facility flows back into the public water system. A cross-connection is a point in a plumbing system where the drinking water supply is or could be directly connected to non-drinking water.

Backflow and cross-connections can cause unpleasant smells and potentially even illness.

The fix is a simple one: a backflow prevention device. These devices come in various types and sizes, from smaller ones suitable for home use to larger models for apartments, offices and other large buildings.

Prevention assemblies required by law

Backflow prevention assemblies are required by law for many types of buildings and plumbing systems.

Nevada state code has, since the 1990s, required builders to install the devices in new commercial properties. The Las Vegas Valley Water District retrofits buildings and water services that existed prior to the regulation’s passage with backflow prevention devices.

Installing prevention devices

The Water District's comprehensive backflow prevention program requires the installation of backflow prevention assemblies on commercial buildings, multifamily properties and irrigation systems.

The Water District determines whether an assembly is required at a specific property. Backflow assemblies are installed according to Water District installation requirements, and the district will inspect installations after they are completed.

Customers who currently have backflow assemblies and those required by law to install them are assessed a monthly service fee to cover the cost of the Water District to maintain, test, and replace backflow prevention devices. Details about service fees can be found in the Las Vegas Valley Water District Service Rules.

Backflow and private plumbing

Even though plumbing code provisions may be rigidly enforced on new construction, experience has shown that "on-site" modifications and alterations of private plumbing are common.

Possible hazards to the public water supply can be created due to cross-connections in private plumbing. These cross-connection hazards may be found in complex mechanical systems or caused by something as simple as a submerged garden hose.

In most cases the only practical way to ensure protection is to install a backflow prevention assembly at the point of service. That way, regardless of what happens inside the customer's property or what changes are made to private plumbing, the public water supply is protected.

Backflow preventer valves for home irrigation systems

If you have any questions about backflow prevention, call our Water Quality Division at 702-258-3215 or contact us via email.