Cross Connection Control Program

Protecting Water Safety
The function of this program is to see that connections between the drinking water system and any other liquid or gas do not pose a threat to the safety of the drinking water. There are two conditions under which cross connections are a problem:
  • The first is when the pressure in the main drops and contaminates are siphoned back into the mains. This can happen when there is a main break or a large fire demand in the area.
  • The second is when the pressure in a building's plumbing system exceeds the pressure in the main. This can be caused by pressure-type boilers or any process connected to the plumbing that heats liquids or gases.
Reduced Pressure Zone Valve
Billerica Water Works has regulations requiring that all commercial buildings have a reduced pressure zone (RPZ) valve after the water meter. While our efforts are directed at commercial properties, homeowners should be aware that they may have cross connections in their plumbing. The most common cross connections are probably a garden hose with a sprayer attached or a hose placed in a swimming pool.

Program Operations
The Head Tester is responsible for surveying all commercial buildings for cross connections. When these are found and cannot be physically separated, a special check valve must be installed. Normally an RPZ valve will be used. The exceptions are the valves on the fire lines, which are double checks. The RPZ valves are tested twice a year and the double checks once a year.