Backflow and Cross Connection Control

Help Us Keep Your Water Safe with Cross Connection Control

North City Water District takes pride in providing safe, high quality drinking water. But keeping water safe is a two-way street. Even though the water that reaches your home or business is pure and clean, contamination can occur at “cross connections” within your own piping system and “backflow” into the public water system.

How to Identify a Cross Connection

A cross connection is a point in a plumbing system where it is possible for a non-potable substance to come into contact with the potable drinking water supply.

For homeowners, cross connections typically occur within irrigation systems, pool systems, hot tub or pond equipment, private fire sprinkler systems, and boiler systems.

When water or other substances flow in the opposite direction of what’s intended—such as the water in an irrigation system flowing back towards the water source once it’s turned off—that cross connection allows contaminants to backflow and enter the public water system—or your own plumbing.

Understanding and Preventing Backflow

There are two types of backflow:

Back-siphonage: this is caused by a negative pressure in the supply line to a plumbing fixture, home, or facility. Backsiphonage may occur during waterline breaks, or when repairs are made to the waterlines, or when shutting off the water supply.

Back-pressure: this can occur when the potable water supply is connected to another system operating at a higher pressure, or with the ability to create pressure—such as booster pumps, pressure vessels, and elevated irrigation systems or plumbing.

As per Washington State Administrative Code (WAC 246-290-490), a Backflow Prevention Device must be installed on any cross connection point on your property, using stringent installation requirements.

Once installed, Backflow Prevention Devices must be tested annually by a certified backflow tester, with the results of the test submitted to North City Water District.

What You Need to Do

If you have any of the items listed below, if you are a business of (most) any kind, or if you raise farm animals, you are required to:

(1) Have backflow prevention in place;
(2) Have a state certified Backflow Assembly Test on your backflow device each year (visit this website to get a list of certified inspectors); and
(3) Send us a copy of your test result.

Backflow Prevention Devices are typically required for the following items, and are often found near your water meter, outdoor taps, or irrigation system connections:

  • Fire sprinkler system
  • Lawn irrigation system
  • Swimming pool
  • Hot tub / jacuzzi tub
  • Decorative fountain
  • Pond
  • Livestock watering system
  • Water makeup lines*
  • Hydraulic boat lifts
    *that supply a boiler or hydronic heating

If you can’t find a Backflow Prevention Device but DO have one or more of the above items on your property, contact us at 206.362.8100 to get the process started.

If you recently purchased a home with a Backflow Prevention Device, give us a call at 206.362.8100 so we can update our records to ensure your device is being tested annually.

If you already have a Backflow Prevention Device in place, but haven’t been receiving our annual testing reminder notices, contact us at 206.362.8100, or fill out the below Reporting Preferences form to receive an annual reminder, either by email or postal mail.

Backflow Device Reporting Preferences

    If You Chose Option 1:

    We will use the email address you entered above, unless you want the reminder to go to someone else, then enter their email address here:

    If You Chose Option 2:

    Additional Comments or Questions:

    Additional Information