Backflow & Cross-Connection Control

Backflow Preventers

Providing safe drinking water to our customers is our highest priority and we follow strict standards to ensure that the public drinking water is safe. Our customers also have a responsibility to help keep the public water supply safe whenever there is an actual or potential hazard for a cross connection.


What is a cross connection?

Cross connections are connections between drinking water and other water or fluids of unknown quality. A backflow preventer may be required if the potential for a cross-connection exists.

Where can I find possible cross connections?

  • Sinks & laundry tubs
  • Outside faucets & hoses
  • Lawn irrigation systems
  • Handheld shower sprayers
  • Boilers
  • Toilet fill valves
  • Fire prevention systems
  • Swimming pools
  • Cooling systems

What is backflow?

Backflow is the undesirable reversal of flow in a water line that is caused either by backpressure or backsiphonage. Backpressure can occur when downstream pressure is higher than the upstream or supply pressure. Backsiphonage can occur when negative pressure or a vacuum is created.

Why are backflow preventers needed?

Backflow preventers are designed and installed to prevent the flow of water backwards through a pipe. These devices protect your public utility drinking water system from back flow created by back siphonage and back pressure.

Who can install and test backflow preventers?

Installation—approved backflow prevention assemblies shall be installed by licensed plumbers and contractors. Testing and Inspection—only a person who is a certified tester registered with TDEC can inspect and/or test backflow preventions assemblies.

How often are backflow preventers tested?

For reduced pressure (RP) devices, they are test annually. For double-check devices, they are tested twice a year. Tennessee Code Annotated 68-221-701-720 requires that all Utility Districts ensure all backflow preventers are in proper working order and are tested annually by certified personnel.

How can I prevent contamination to my drinking water?


  1. Submerge hoses in buckets, pools,tubs, sinks, ponds, etc.
  2. Use spray attachments without a backflow prevention device
  3. Connect waste pipes from water softeners or other treatment systems to the sewer, submerged drain pipe, etc
  4. Use a hose to unplug blocked toilets, sewers, etc.


  1. Keep the ends of hoses clear of all possible contaminants
  2. Install an approved backflow prevention assembly on all underground lawn irrigation systems
  3. Leave an air gap, or space, between valves or faucets and any place water can collect


What are my responsibilities?

If your water use introduces the potential for a cross-connection, you must:

  • Have a backflow device installed by a licensed plumber or contractor. (HPUD will provide a list per request)
  • Repair the device as needed. HPUD will have the device tested annually and after any repairs for a $45 fee. If you choose to have your device tested through another service, you must send passing results to HPUD to avoid water service termination. (HPUD will provide a list of certified testers.) If your device fails, you must have it repaired within 30 days of receiving a failure letter. An inspector from HPUD will then retest the device. If the device fails again you have 15 days to have it repaired or your water service will be terminated. Note: Water supply to the device must be on for testing.


Inspections Services Coordinator
Telephone: (865) 922-7547

Inspector, New Residential Commercial Developments
Telephone: (865) 922-7547