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Cross-Connection and Backflow

Cross-Connection and Backflow

Cross-Connection and Backflow Defined

Common cross-connections in homes and commercial properties:
  • Submerged hoses
  • Lawn sprinkler system
  • Fire protection systems
  • Boilers
  • Toilet tank
  • Tank with submerged inlet
  • Solar heating system
  • Cooling tower
  • Swimming pool
  • Photography equipment

Backflow is any unwanted flow of used or non-potable (non-drinkable) water or substance from any domestic, industrial or institutional piping system into the pure, potable (drinkable) water distribution

Cross-Connection is any physical connection between a potable (drinkable) water supply and non-potable (non-drinkable) water, or other substance of unknown or unsafe quality. Cross-connections can allow contamination or pollution of the public water supply as a result of backflow.

Northglenn strives to keep the water flowing in the right direction at all times. However, this is not always possible; that’s why Northglenn maintains a Cross-Connection Control Program. This program seeks to identify all existing cross-connections within the city's water distribution system. Once a cross-connection has been identified, the city and property owner then protect the public water system from potential pollutants through the use of backflow prevention devices, assemblies and practices.

Cross Connection FAQ

1. What is backflow?

Backflow is the reverse flow of water, other liquids or gas into the distribution pipes of a potable water supply from any unintended source. An unfortunate example of backflow occurred in 1979 in Virginia when a routine visit by an extermination company connected highly toxic insecticide chemicals barrels up to the water lines in a homeowner’s residence. The local water company was working on a water main line break and flushed their hydrants to clear the repaired main line. The chemicals were back siphoned into the house and into the city’s water main. Testing of the supply lines showed levels five times higher than safe for consumption for six days after the incident.

2. What is a Backflow Prevention Assembly (BPA)?

A BPA prevents reverse flow of water into a supply system. In general, BPAs consist of check valves, test ports and shut-off valves. When a backflow occurs, the check valves close, preventing the reversal of flow into the supply line.

3. What types of BPA does the City of Northglenn require?

In general, the city requires Reduced Pressure Zone type backflow prevention assemblies at all commercial, industrial, non-single-family-residential service connections and on irrigation lines. There are some exceptions to this requirement.

4. What are the requirements for installing BPAs?

The city regulations require BPAs to be installed after the service connection (water meter) and before any plumbing branches. This is known as “containment” protection, and protects the city’s water supply line from potential contaminants found in a commercial, industrial or multi-family residential facility. BPAs must be installed in accordance with all requirements in the Municipal Code by a licensed plumber, then tested by a certified backflow assembly testing technician.

5. Who does the annual testing of BPAs?

BPAs must be tested by a certified backflow assembly testing technician, who holds a current certification from either the ABPA or the ASSE. The technician’s certification type (ABPA or ASSE), certification number and expiration date must be shown on the BPA test report.

6. What to do with the passing test report for your BPA?

Annual test reports for BPAs that pass, must be submitted to the city, preferably by e-mail to: within 10 days after the test has been done. The report must be submitted to the city by the certified backflow assembly testing technician, or their associated company. You must retain copies of backflow reports and maintenance records for a minimum of three years.

7. The certified backflow assembly testing technician provided me with a failing test report for my BPA, what am I required to do with the report?

If the BPA fails the test, the city must be notified by phone or e-mail the same day of the failed test and the report must be submitted within 10 days after the test has been done. The BPA must also be repaired and retested or replaced within 30 days after the failed test has been reported to the city. You must retain copies of backflow reports and maintenance records for a minimum of three years.

8. What if the failed BPA is not repaired and retested or replaced?

Failure to comply with this requirement could result in removing the cross-connection or suspending water service until compliance is achieved

Cross-Connection for Business

Annual Inspections

As part of the city's Cross-Connection Control Program, the city conducts periodic inspections of commercial properties looking for potential risks to the water distribution system. If the plumbing system inside of your building was built to code, these risks will be well-managed. However, older buildings that were built to previous codes may need to be brought up to current plumbing requirements.

Furthermore, all commercial, industrial and non-single family residences (townhomes and apartments) are required to have approved backflow devices installed and tested annually to stay in compliance with the City’s Cross Connection Control Program.

Cross-Connection Business Survey


Alex Arnold
Backflow Prevention Specialist
P: 303-450-4026
F: 303-450-4044