Cross-Connection Control and Backflow Prevention


A cross connection is any actual or potential connection between the City’s potable water system and a source of contamination or pollution. Backflow can occur when water or other liquids flow through an unprotected cross-connection into the water system, often caused by a back pressure or back siphonage event. Backflow into the City’s water system could send harmful pollutants or bacteria into the City’s drinking water and create a drinking water emergency. Drinking water is protected through the installation of backflow prevention devices at cross-connections to prevent harmful liquids from backflowing into the water system. 


The Water Division is responsible for testing three types of backflow prevention devices:

  • Double Check Valve Assembly (DCVA)
  • Pressure Vacuum Breaker (PVB)
  • Reduced Pressure Zone Device (RPZ)

Testable devices are tested once or twice per year (based on device type), and results from each test are retained by the Water Division and reportable to MassDEP.


Before installing a backflow prevention device, approval must be obtained from the Water Division by submitting a design data sheet. Once installed, the property owner must contact the Water Division to schedule the device to be tested. The cost for testing a backflow prevention device is reflected in Specialty Fees Section (PDF).

Irrigation Backflow Prevention Devices

If you are installing an irrigation system, the associated backflow prevention device must be tested by the City before the irrigation system is placed into service. Irrigation systems’ backflow preventers are only required to pass an initial test, and are NOT subject to annual or semi-annual testing.


The City performs testing of backflow prevention devices on private property in accordance with state’s regulations, which are located here: MassDEP Cross Connection Control Program Regulations - 310 CMR 22.22. Property owners will be assessed a fee for each test performed on their water bill.

If a backflow prevention device fails to meet MassDEP’s performance standards, the City will notify the property owner of the device failure. The property owner is responsible for replacing or repairing the device, and having the device re-tested within the timeline specified by the regulations. Property owners are responsible for fees associated with each re-test.

PLEASE NOTE: Water service is subject to disconnection for properties that do not replace or repair failed backflow prevention devices within the required timeline.