Cross Connections

Information for Residential Home Owners

What is a cross connection?

A cross connection is any actual or potential connection between the public water system and any other non-potable supply. What this means is if you connected your plumbing in your house to anything that you would want to drink, then you have created a cross connection. Some examples of creating a cross connection are:

  • Taking a garden hose and submerging it into a swimming pool
  • Connecting a chemical device to a hose for watering
  • Connecting your plumbing to a hot water system or air conditioning system that uses a chemical
  • An underground irrigation system
  • A private well connected into the public water system

Why is this a hazard? Because under normal conditions, the water from your water supply is under positive pressure. That is why when you turn on the faucet, water comes out because it is under positive pressure. There maybe circumstances where the pressure in the system is lost and a vacuum is created. This would cause water to be sucked back into the system.

Let’s say you are filling your swimming pool. You turn on the hose and leave it in the pool to fill. The hose becomes submerged in the water. While the hose is in the water, a contractor working down the street accidentally breaks the water main. The broken water pipe can cause a complete loss of pressure and even a vacuum in the water system nearby. So the hose you have sitting in the pool will start to suck the water out of the pool and back into your house plumbing. Once the water pipe is repaired and system pressure is restored, you now have a house full of dirty water which will come out of any faucet. This is referred to a backsiphonage.

Another scenario is a home owner that has a private well that he/she uses for watering outdoors. The homeowner decides they want to connect the well into the house plumbing so they have more water in the house. The well pump has a higher pressure than the pressure in the house and the well is contaminated with Arsenic. Once the well is connected into the house, the contaminated water is forced back into the house plumbing and back out to the street where the contaminated water flows into other homes. This is referred to as backpressure.

We can prevent these scenarios from happening by installing a backflow prevention device in the house plumbing. A backflow prevention device will only allow the flow of water in one direction. It will not allow water to be sucked back into the system from backsiphonage or from backpressure. A backflow prevention device will completely protect your water system from cross connections.

There are different types of backflow prevention devices that are used for different situations. Many types of backflow devices are required to be tested periodically to ensure that they function properly. If you have any questions or concerns about cross connections at your home, please contact our office and we will be happy to assist you.

Information for Non-Residential (Commercial) Properties

All non-residential properties are required to be surveyed by the Whitinsville Water Company (WWC).  A cross connection survey consists of a licensed surveyor from WWC inspecting all of the plumbing at the property to identify all cross connections and ensure proper backflow prevention devices are installed at all cross connections.  WWC has conducted surveys for nearly all non-residental properties served by the water company.  However, if there is a change of use at the property WWC is required to reinspect the property.  All new non-residental properties must complete a Backflow Prevention Device Design Data Sheet and submit plumbing plans to WWC for approval prior to construction.  After a new property is constructed, WWC is required to conduct a cross connection survey of the newly constructed property.  All cross connection surveys are completed using a MADEP approved survey form.

As noted above, proper backflow prevention devices are required to be installed at all cross connection locations.  The proper device varies depending on the degree of hazard.  Some devices are required by State Regulations to be tested annually or semi-annually.  WWC has State licensed device testers and will perform the required test of each device to ensure proper operation.  WWC maintains a database of all known devices in the system and testing history of each device.