Cross Connections and Backflow Prevention

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For Cross Connection & Backflow Prevention program questions or assistance​ not related to billing, contact:


Public Works - 8:00 a.m. to 4:00 p.m. Monday-Friday (except holidays)

For billing questions or assistance contact Customer Service at:


Customer Service - 7:30 a.m. to 5:30 p.m. Monday-Friday (except holidays)

​​How do I submit my backflow test ​​report?

​To submit the backflow test report, please complete the fillable form

​​What is a cross connect​​​ion?

Any piping arrangement which allows a potable (drinking) water system to be connected to a non-potable system.

What does backflow m​​ean?

The u​ndesirable reversal of the flow of water or other substances into the potable water distribution supply. It can be caused by backpressure, backsiphonage or combination of both.​
The most common source of residential cross connection is a garden hose. For example, the end of the hose might be submerged in a non-potable (undrinkable) source or it might be connected to a fertilizer sprayer. If the water pressure drops, contaminated water could get sucked back into your water pipes, which could pose a health risk to you and your family.

Prevent water backflow  

How do you protect yourself from backflow situations?

  1. Keep all hoses and faucets away from direct contact with possible contaminants. 
  2. Never submerge hoses in buckets, pools, tubs, or sinks. 
  3. In​ the event of loss of water pressure, you need an air gap. Otherwise the hose will act like a straw and suck the liquid backwards.
  4. Protect yourself by installing inexpensive backflow protection devices on all hoses and threaded faucets in your home. These devices are available at hardware and home improvement stores for about $4-10 each. Backflow vacuum breakers provide safety valves that prevent liquids from flowing backwards into a hose or faucet.

Specialized backflow prevention devices are available for more elaborate installations, such as:

  • built-in lawn irrigation sprinklers
  • hot water boilers
  • in-ground swimming pools
  • heat exchangers
  • active solar heating systems,
  • private wells

Devices are also available for specialized commercial locations such as:

  • dry cleaners
  • car washes
  • laboratories and manufacturers

Backflow devices ensure that potentially contaminated water cannot be drawn back into the public water supply from a business or residence in the event of a negative water main pressure situation. If you receive a letter from the Water Utility informing you that a device is due for certification and inspection, please respond as quickly as possible to protect water quality and safety. Proper maintenance of backflow prevention devices requires a periodic certification, followed by a City of Ann Arbor inspection, and the subsequent annual reporting of those results to the Michigan Department of Environment, Great Lakes, and Energy (EGLE). For more information on specialized backflow requirements, contact a plumber certified by EGLE (PDF) on backflow prevention devices, or the City of Ann Arbor Backflow Inspection line at 734.794.6339​​​.