Backflow Prevention Program

Properly working backflow prevention assemblies keep drinking water clean and safe.

Latest Updates

The City of Boulder’s Backflow Prevention Program is moving online!

Starting on June 7, the City of Boulder is implementing an online portal for testers to enter backflow prevention assembly test reports.

What this means for certified testers:

  • Beginning June 23, all backflow tests must be entered through the online portal. Emailed tests will no longer be accepted after June 22.
  • Every certified tester must have a log-in to use the portal.
    • Testing companies can have non-tester staff enter tests. They will just need to have a separate login for each tester certification.
  • Beginning June 23, all backflow tests must be entered through the online portal. Emailed tests will no longer be accepted after June 22.
  • There is currently no cost for submitting test reports through the city’s portal.
  • The portal is accessible via mobile devices and on your computer, with an option to print the report.

Why is the city implementing the online portal?

The City of Boulder administers more than 7,000 backflow accounts. Currently, tests for all accounts must be hand-entered into the city’s database. The portal modernizes the system, ensuring more accurate data collection and better use of utility rate-payer dollars.

Backflow Prevention Program

State regulations require the City of Boulder to maintain a Backflow Prevention Program to track the installation and annual testing of backflow prevention assemblies on all hazardous cross-connections (potential points for contamination and backflow).

This applies to all commercial/industrial, large multifamily and some smaller multifamily and residential customers connected to the city's water supply.

Currently, the Backflow Prevention Program cannot recommend testers nor does the city keep a list of testers.

Get Backflow Prevention Compliance


At this time, residential customers/homeowners do not have to comply with the Backflow Prevention Program requirements unless:

  • There is an auxiliary water source on the property;
  • There is a dedicated irrigation line tapped off of the main; or
  • There is another hazard as identified by the Backflow Prevention Program (including the existence of a well on the property).

The Backflow Prevention Program requirements are not meant to contradict building, fire or plumbing codes, which may require a residence to have a backflow prevention assembly like those required on residential sprinkler systems. When backflow prevention assemblies are otherwise required, they must be installed, but will not be tracked by the Backflow Prevention Program.


Multi-family properties include 2 or more separate dwelling units served by one meter connection. Multi-family properties generally must comply with backflow prevention installation and annual testing requirements—similar to commercial properties.

  • Small multi-family property exemptions - Small multi-family properties with 8 units or less may qualify for an exemption from the city’s backflow prevention requirements (installation and annual testing). To qualify, properties must meet all of the criteria listed on the Small Multi-Family Exemption Application. The following FAQ’s will help to fill out the application. An Exemption Application must be submitted for each property requesting an exemption. Please be sure to check all boxes on the form and initial next to them to insure your application is approved. Applications can be submitted by mail to 5605 N 63rd St., Boulder, CO 80301, fax: 303-530-1137 or email to


Unless otherwise permitted by the Backflow Prevention Program all commercial properties must comply with the installation and annual testing of backflow prevention assemblies.

General Compliance Information

In accordance with Regulation 11 - Section 11.39 of the Colorado Primary Drinking Water Regulations and the Colorado Department of Public Health and Environment, all properties listed below must comply with the state regulation for the installation and annual testing of backflow prevention assemblies.

There is no "grandfather clause" associated with this regulation, meaning that all existing and all newly constructed properties have to install and test backflow prevention assemblies as needed. View information on installation criteria and/or which backflow prevention assemblies are required to be installed and tested annually. City staff may need to survey properties to determine whether cross-connections are present, what the degree of hazard is or if approved assemblies are installed in proper locations.

State regulation and the Backflow Prevention Program are, in general, responsible for monitoring the installation and annual testing of "containment" assemblies. To be a true containment assembly, the assembly must be installed after the meter but prior to any plumbing branches. It is possible that two containment assemblies may be required if branches exist such that a single assembly cannot be used.

Other assemblies may be required inside a property by plumbing code. These other assemblies are called "isolation" assemblies because they isolate internal hazards. The Backflow Prevention Program does not track these assemblies unless there is a specific need. However, it is strongly recommended that isolation assemblies are tested annually along with containment assemblies as they can keep water inside the property safe for consumption. Plumbing code may allow some points of isolation to be protected by devices (non-testable assemblies) such as dual checks.

If it is determined that a specific isolation assembly is to be tracked, the Backflow Prevention Program will require annual testing of both the containment assembly and the specific isolation assembly. If true containment cannot be achieved, the Program Coordinator will determine if isolation assemblies can be tested instead of a single containment assembly. However, whenever possible, containment will be required.

Irrigation and pressure vacuum breakers

Pressure vacuum breakers that are currently being used for backflow prevention on dedicated irrigation lines are acceptable as long as the assembly passes annual tests. City of Boulder Design and Construction Standards 5.09(c)(4) states:

  • Reduced pressure assembly required: All irrigation systems with a separate, metered service line shall have a reduced pressure principle assembly installed in compliance with all applicable city regulations and standards.
  • Therefore, if a pressure vacuum breaker fails and requires replacement it should be replaced with a Reduced Pressure Zone Assembly.

Test Your Backflow Prevention

Check your assembly

  • Your existing backflow prevention assembly has been tested before and should have a tag from the previous tester that shows the tester's or testing company phone number.

Find an assembly tester

  • Plumbers and contractors usually hold their own certification or know someone who can test your assembly.
  • Testers must hold a current certification from either The American Backflow Prevention Association, or The American Society of Sanitary Engineers. Both organizations re-test every three years and anyone testing a backflow prevention assembly must have a current certification on the date of the test.

Assemblies on fire lines

Submit test reports

  • Testers or owners are required to submit test reports to the Backflow Prevention Program at within 10 days from the test date.
  • This information will be recorded by the program and testing will not be required until the following year.
  • Water suppliers, testers and customers must all retain test report records for three years.
  • The City of Boulder's Backflow Prevention Program uses a Universal Test Form created, used and accepted by backflow programs across Colorado. Incomplete or incorrectly filled out forms will be returned to the tester.
  • Backflow prevention assemblies are tested by certified testers who use gauges to either add or relieve pressure to determine if the internal parts are working properly. This information is recorded on a backflow prevention assembly test report.
  • The City of Boulder uses a Universal Test Form created, used and accepted by backflow programs across Colorado. Incomplete or incorrectly filled out forms will be returned to the tester.

Failing tests

  • The Backflow Prevention Program must be verbally notified the same day and the failing test should be submitted within three days.
  • Backflow prevention assemblies that fail a test must be repaired and/or replaced immediately.
  • If the repair or replacement cannot be made immediately, the Backflow Prevention Program must be notified and a compliance plan must be established.
  • As a failed backflow prevention assembly test represents a direct cross-connection, failure to repair/replace and test an assembly can result in suspension of water service if the Backflow Prevention Program determines that the cross-connection represents an immediate risk to public health.