Cross Connections

Our goal is to have safe drinking water for all of our residents. 

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State health regulations require that all water providers have a program that identifies and eliminates cross connections to our public water system. 

Our program works to identify and eliminate any possible cross connection systems that could be a risk vital towards us achieving this goal. We want to ensure that from the first user to the very last user on our water line has safe and drinkable water and that nothing has entered the system in between.

What is a Cross Connection?

A cross connection is the arrangement of a piping on a building’s plumbing system which could result in the backflow of contaminants into the public's drinking water supply system.

What is backflow?

Backflow refers to a change in a water systems flow from a home or building’s plumbing system and pushes excess water back into the public drinking water supply.  A common backflow occurrence can happen when there is a pressure drop in the public's drinking water supply system such as a water main break.

There are two types of backflow:

Backsiphonage - this happens when there is a loss of pressure in the main water supply. This creates a siphon in the plumbing system which can draw water out of a sink, bucket or tank, and back into the water system.

Backpressure - This happens when a source of pressure (such as a boiler) creates a pressure greater than what is normal for the main water system. This can cause contaminated water to be pushed into the plumbing system through an unprotected cross connection.

Common causes of backflow contamination can occur when:

  • A pressure drop in the public's drinking water supply system such as a water main break
  • A plumbing fixture such as a boiler or pump generates more pressure than the water supply system can handle which can lead to water flowing back into the public drinking water supply system
  • Household sprinkling systems that contain pesticides, herbicides, bacteria, and other contaminants
  • Garden hoses that are submerged in swimming pools, mud puddles, utility sinks, buckets, etc.

How does this affect you?

Backflow can introduce contaminants into the drinking water supply which can have dangerous, even lethal consequences.

We have developed this program to protect you from the potentially harmful effects of a faulty cross connection system which can include:

  • Public health hazards that can lead to death
  • Damage to physical property
  • Contamination of the public water system

How you can help prevent a backflow.

PLEASE NOTE: Compliance with this program is mandatory.

State and local regulations and plumbing code require approved backflow prevention methods to be installed at every point of potable water connection and use. Fines, penalties, and the loss of water service are all possible if non-compliant.

Want to prevent a backflow occurrence at your home or office? Click here to learn about different prevention devices you can purchase.

Per our City Ordinance, which regulates our Backflow Prevention Program, our inspectors conduct survey inspections of the water system in a home or building with your supervision. This survey is needed to identify potential cross connection systems that require the installation of a Backflow Prevention Device. 

In the event that you must purchase or provide a backflow prevention device, please use our Backflow Prevention Assembly Test Report to submit to the Water & Sewer Division of the DPW. 

Backflow Prevention Assembly Test Reports can be faxed to (248) 391-4895 or emailed to

Want to learn more about how to protect yourself and your community from backflow? Check out this helpful booklet with the 50 most common questions about Cross Connections! 


Should you need further information on the Backflow Prevention Program, please contact our Backflow Prevention Control Officer at 248.391.3777 or email:

Click here for a list of some of the Certified Backflow Testers in the Auburn Hills area