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Cross-Connection Control & Backflow Prevention

A cross-connection is an actual or potential link between the potable water supply (water safe for human consumption) and a non-potable source (any other type of liquid, gas or substance not fit for consumption and that can affect water quality).

A cross-connection can be avoided by eliminating the link between the two sources. If the link cannot be removed, then the potable water supply must be protected through the use of a backflow prevention assembly.

The most common cross-connection is a typical garden hose, which is left submerged in a volume of water or other fluid (i.e. a garden hose left in a bucket of soapy water). Other cross-connections include kitchen sprayers in a sink filled with dirty water, irrigation systems, boilers and other appliances supplied by water.

The Cross-Connection Control Unit of the Miami-Dade Water and Sewer Department was established in order to implement the rules of Section 62-550 of the Florida Administrative Code, which requires public water systems to establish cross-connection control programs to detect, prevent and eliminate cross-connections that may create an imminent and substantial danger to the public health.

By working together, we can protect our drinking water for future generations. For more information, email [email protected].

Backflow Prevention

Backflow is the undesired reversal of flow of water and/or other substance into the potable water supply, via a cross-connection, due to a change in pressure caused by either Backpressure or Backsiphonage.

Backpressure is a type of backflow condition that exists when the pressure in the downstream side of the customer’s piping system becomes elevated greater than the supply pressure at the potable water system. Backsiphonage is a type of backflow condition that exists when the pressure in the potable water supply system becomes lower than atmospheric pressure (14.7 psi).

The potable water supply can be protected from backflow by eliminating all cross-connections or through the use of the proper backflow prevention assembly.

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Backflow Prevention Assembly

A backflow prevention assembly or backflow preventer is a mechanical valve arrangement, which is designed to prevent the "backflow" or reversal of flow of water, once it has passed through the valve. There are different types of backflow preventers for different uses, and different degrees of hazard.

Because the backflow preventer is a mechanical device with springs, moving parts and rubber seating surfaces, which wear over time, it must be tested upon installation and every year thereafter to ensure that the assembly is working properly.

A Certified Tester is a person who has completed a 40-hour training course in backflow prevention assembly testing and has passed a proficiency test to prove his/her knowledge.

Many plumbing, fire sprinkler, lawn irrigation and backflow preventer testing companies are listed in the local telephone directories. Read below for information on becoming a Certified Tester.

The Miami-Dade County Code, Chapter 32, Article VIII requires Backflow Prevention Assemblies to be installed on certain services depending on the degree of hazard, the type of service (i.e. fire suppression system, irrigation system, and domestic water system), and the use of the facility.

A licensed plumber or contractor may install a Backflow Prevention Assembly.

Companies (not the Department or the County) determine the cost of the service to have Backflow Prevention Assemblies tested and installed.

However, there is a permit fee associated with having a Backflow Prevention Assembly installed. The fees are determined by the Building Department of the city in which you are having the assembly installed.

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Becoming a Certified Tester

Join the Miami-Dade Water & Sewer Department's Cross-Connection Control Unit's list of companies with certified testers.

Simply fill out the Certified Tester Information Form , along with copies of your:

  • Business/Contractor License, if applicable,
  • Certificate of Liability Insurance,
  • Backflow Prevention Assembly Test Kit (s) Calibration Certificate,
  • Backflow Prevention Assembly Tester Certificate (s), and
  • Contractor License of the Backflow Prevention Assembly Testers, if applicable.

and fax to 786-268-5485, or mail to:

MIAMI FL 33136

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Backflow Prevention Assembly Test Report

Entering tests on-line is very simple. The first step is to logon using your user name and password.

  • Every tester has a unique user name and password.
  • User names and passwords are NOT case sensitive.
  • Miami-Dade Water and Sewer Department will supply this information.

Call 305-547-3046 for more information.

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County Code and Brochures

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Forms, Lists and Design Standards

The following link of certified backflow prevention assembly testers contains local companies that provide the backflow testing service. These companies employ individuals that have taken and passed a ‘Certified Backflow Prevention Assembly Tester’ course as required by the Florida Department of Environmental Protection. 

Please note that the Miami-Dade Water and Sewer Department does not endorse any of the listed companies.

Specifications for Backflow Prevention Assemblies




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Page Last Edited: Wed Jun 19, 2019 10:22:52 AM

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