Backflow Prevention

What is backflow?

Water systems are designed to flow in one direction.  However, a drop in pressure or a break in a water line can send water flowing in the opposite direction - drawing contaminants and other chemicals into our water system.  This reversal of flow is called backflow, or back-siphoning.  Backflow into our public water system can pollute or contaminate the potable (drinking) water making the water unsafe to drink.  The Henry County Water Authority has a responsibility to provide safe drinking water under all foreseeable circumstances. 

In 1974, the Federal Government established the Safe Drinking Water Act (SDWA), protecting human health from contaminants in drinking water.  Many actions are required to protect our drinking water and its sources, including administering a program which prevents backflow at cross connections. 

What is a cross connection?

Each customer connection to our public water system represents a potential cross connection and must be protected in order to prevent backflow into our public system.  Cross connections are generally unintentional and can happen anywhere potable water is connected with non-potable water.  Installation and maintenance of appropriate backflow prevention devices prevent contamination via cross-connection. 

The customer's connection to the public water system begins at the water meter and all piping on the customer's side of the meter is considered part of a non-public system. 

Our Cross Connection Control Program:

Our Construction and Inspections Department administers our backflow prevention program in accordance with our Cross Connection Control Program Manual. 

This includes:

  • Determining whether a customer must install a backflow prevention device and if so, which type.
  • Developing and maintaining standards and specifications for installing backflow prevention assemblies.
  • Inspecting newly installed backflow preventers.
  • Maintaining records of annual backflow device test reports. 
  • Backflow Prevention Assembly Test Data and Maintenance Report.  (Fillable .pdf Test Report)
  • Certifying backflow testers and maintaining an Approved Tester List.
  • Application to be placed on HCWA Approved Tester List.

Customer is responsible for having their backflow device(s) installed according to our specification and tested by an approved tester.


Commercial/Industrial Customers

Backflow requirements for businesses are evaluated on an individual basis when a water account is established.  Businesses classified by HCWA as "high risk" are required to install appropriate backflow prevention devices and have them tested annually

Businesses classified as "high risk" include:

Medical/Dental offices, funeral homes, multi-tenant retail spaces, and/or any business with a fire sprinkler system. 

If a backflow device is already installed:

You are responsible for having it tested annually by an approved backflow tester.  We will notify you by mail when your device is due for testing.  Tester should submit test results to HCWA. 

(Provide a copy of the reminder letter to your approved tester.  This will give the tester the information needed to submit the results.)

If you are required to install a new backflow device:

  • Have the device installed according to our specification by a licensed plumber.
  • Once installed, contact us to schedule an inspection.  770-914-3688 or backflow@hcwa.com
  • Contact an approved tester to test the device.  The tester should submit test results to HCWA.
  • The backflow device will require annual testing by an approved tester.  We will notify you by mail when it is time for your annual test. 

(Provide a copy of the reminder letter to your approved tester.  This will give the tester the information needed to submit the results.)

HCWA does not install or test commercial backflow devices.

If test reports are not provided as required, HCWA is authorized to suspend water service. 


Residential Customers

Per Georgia State Plumbing Code, all homes constructed after 2001 should contain a backflow prevention device and thermal expansion tank - creating a closed system.  (Homes built prior to 2001 may not have these capabilities inside the house.)

Backflow prevention devices not only protect against potential backflow, but also seal water off inside the customer's home, possibly creating higher pressure on an existing plumbing system.  For some homeowners, a spike in pressure could set off the relief valve on the hot water heater, causing additional damage to the plumbing system and/or home. 

Thermal Expansion Danger

Water expands in volume as its temperature rises.  The extra volume caused by thermal expansion must go somewhere.  If not, the heated water creates an increase in pressure.  The temperature and pressure in the water heater is reduced when hot water is withdrawn from a faucet and cold water enters the tank.  Pressure can also be reduced by water flowing back into the public water system.  However, when a check valve, pressure-reducing valve or backflow preventer is installed in the service pipe, a "closed system" is created.  Provisions must be made for thermal expansion. 

What the homeowner should do to ensure protection from thermal expansion:

  • The homeowner should check to see that an expansion tank is in place.
  • If there is any doubt, the homeowner should contact a licensed plumber. 

Customers should ensure pressure relief or thermal expansion devices are installed and operating properly on or within their plumbing systems. 

HCWA will not be responsible for any plumbing difficulties that arise as a result of non-existing or improperly installed thermal expansion or pressure relief equipment. 

Below are links to various types of Thermal Expansion Devices commonly used in homes:

Devices can be found at most hardware stores. They are made from a variety of manufacturers including:

For additional information on backflow prevention and thermal expansion, please refer to the following documents:


Cross-Connection Control Program

100 Westridge Industrial Boulevard

McDonough, Georgia 30253








Backflow Prevention Assembly Test Data and Maintenance Report

HCWA Approved Backflow Testers List

Application for Listing for Backflow Prevention Testers


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Henry County Water Authority | 1695 Highway 20 West | McDonough, GA 30253 | Phone (770) 957-6659 | Fax (678) 583-2466