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Cross Connection Control

The Manitowoc Public Utilities Cross Connection Control Program is designed to prevent backflow or backsiphonage of contaminated water into the drinking water supply. The MPU program has been around for many years, but has recently been updated in response to changes in State regulations in an effort to better protect potable (drinking) water systems from potential contamination. This program is run in accordance with the Wisconsin Department of Natural Resources (WDNR) and NR810.15 of the Wisconsin Administrative Code. MPU is required to report to the WDNR annually on the status of testing and inspecting cross connections at the businesses and homes that we serve.

State law mandates that MPU perform cross connection inspections of its more than 13,000 residential water customers. Utilizing our State approved program, MPU coordinates the residential cross connection inspection in conjunction with our scheduled meter replacement program. Residential meters are replaced on a 20-year cycle, so that is why your home may have been selected for an inspection when your neighbor's did not. Eventually, all residential customers will be inspected. Commercial, industrial, and institutional customers are inspected for compliance on a more frequent basis, as often as every two years.

If you have any further questions on Wisconsin Administrative Code NR810.15 regarding cross connections, you are encouraged to contact the WDNR at 920-662-5414.

If you have questions regarding the MPU Cross Connection Control Program, please call the MPU Business Office at 920-683-4600.

Thank you for your cooperation! Remember, by working with us to protect water quality, you will be protecting yourself, your family, and your neighbors.


What is a Cross Connection?

A cross-connection is an actual or potential connection between the safe drinking water (potable) supply and a source of contamination or pollution. State plumbing codes require approved backflow prevention methods to be installed at every point of potable water connection and use. Cross-Connections must be properly protected or eliminated.

How Does Contamination Occur?

When you turn on your faucet, you expect the water to be as safe as when it left the treatment plant. However, certain hydraulic conditions left unprotected within your plumbing system may allow hazardous substances to contaminate your own drinking water or even the public water supply.

Water normally flows in one direction. However, under certain conditions, water can actually flow backwards; this is known as Backflow. There are two situations that can cause water to flow backward:

  1. Back Siphonage: May occur due to a loss of pressure in the municipal water system during a fire fighting emergency, a water main break or system repair. This creates a siphon in your plumbing system which can draw water out of a sink or bucket and back into your water or the public water system.
  2. Backpressure: May be created when a source of pressure (such as a boiler) creates a pressure greater than the pressure supplied from the public water system. This may cause contaminated water to be pushed into your plumbing system through an unprotected cross-connection.

In the Bathroom - Hand Held Shower Fixture

The hand held shower fixture is compliant if:

  • When shower head is hanging freely, it is at least 1" above top of the flood level rim of the receptor (tub)
  • Complies with ASSE #1014
  • Has the ASME code 112.18.1 stamped on the handle

In the Bathroom - Toilet Tanks

There are many unapproved toilet tank fill valve products sold at common retailers which do not meet the state plumbing code requirements for backflow prevention.

  • Look for the ASSE #1002 Standard symbol on the device and packaging
  • Replace any unapproved devices with an ASSE #1002 approved anti siphon ball-cock assembly. Average cost is typically $12 to $22 at home improvement stores
  • Verify overflow tube is one inch below critical level (CL) marking on the device

In the Kitchen

Hoses and water treatment devices may create a potential backflow hazard if not properly isolated with backflow prevention methods.

Insights to Protect Your Drinking Water


  • Keep the ends of hoses clear of all possible contaminants.
  • Make sure dishwashers are installed with a proper "air gap" device.
  • Verify and install a simple hose bibb vacuum breaker on all threaded faucets around your home.
  • Make sure water treatment devices such as water softeners have the proper "air gap", which is a minimum of one inch above any drain.


  • Submerge hoses in buckets, pools, tubs, sinks or ponds.
  • Use spray attachments without a backflow prevention device.
  • Connect waste pipes from water softeners or other treatment systems directly to the sewer or submerged drain pipe. Always be sure there is a one inch "air gap" separation.

Public Health & Safety

To avoid contamination, backflow preventers are required by state plumbing codes wherever there is an actual or potential hazard for cross-connection. The Wisconsin Department of Natural Resources requires all public water suppliers to maintain an on-going Cross­ Connection Control Program involving public education, onsite inspections, and possible corrective actions by building owners if required.

More Information

WI Department of Commerce

WI Department of Natural Resources

Environmental Protection Agency (EPA)

Cross-Connection Control / Backflow Prevention


To help safeguard the public water system, MPU developed a Cross Connection Control Program, which will be administered as defined in Chapter 17.105 of the City of Manitowoc Municipal Code.

MPU Cross Connection Control Program

Affidavit of Compliance

Cross Connection Control Inspection Form

Device Checklist