Help Keep Our Drinking Water Safe

Water is essential for life! We all know this for a fact, but we also depend on it to make our lives more comfortable, especially during the warmer months of the year when our usage increases. During the summer we are busy with many outdoor chores involving water such as filling a swimming pool, giving the family pet a bath, washing our cars, cleaning house siding and decks and watering or treating lawns and plants. But regardless the activity or time of year, it is important to keep in mind that it is everyone’s responsibility to protect our safe drinking water supply throughout the year.

Numerous tests are performed on Clarksville’s water by the expert staff at the water treatment plant to provide citizens with the safest and highest quality drinking water possible. We are proud to report that our drinking water meets and exceeds all federal and state drinking water standards set by the Environmental Protection Agency (EPA). The department goes even further to ensure the safety of our drinking water supply with our ongoing backflow and cross connection prevention program. This program is mandated through federal and state regulations and City code.

Both backflows and cross connections can pose serious threats to our drinking water supply. The following section will explain why and how we can work together, as a responsible community, to prevent these threats. First it is important to know how a backflow or cross connection can occur and how they can result in contaminated water.

What is Backflow?

Water distribution systems are designed with the intention of the water flowing in a certain direction—from the distribution system to the consumer. However, hydraulic conditions within the system may deviate from the “normal” conditions causing a change of pressure in the system and resulting in water flow in the opposite direction or backwards. Therefore, it is possible (and common) for the water to flow in the opposite direction in unprotected systems. This is called backflow. Backflow is dangerous because it can allow chemicals, bacteria or pollutants to flow into drinking water in your plumbing system and the drinking water can become contaminated and unusable or even possibly deadly.

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What is Thermal Expansion?

Thermal expansion is a dangerous increase in water pressure due to heated water having nowhere to go in a closed system.

All backflow prevention devices and many water meters are manufactured with check valves in them to prevent water from flowing in reverse and into our water system. The valves are a safety feature that protects the city water supply from contamination; however, they create a closed water system.

The closed system is not a problem until water is heated with little or no space for expansion. The result is a dangerous increase in water pressure that can damage water heaters, plumbing systems and fixtures. Thermal expansion may lead to more serious problems and may also contribute to water heater ruptures and in rare cases explosions. But, there’s a solution!

What can be done about thermal expansion?

There are signs to look for to identify potential problems before more serious ones occur. Please learn the signs of thermal expansion from the list below.

Some signs of thermal expansion.

  • the relief valve on the water heater drips during the recovery cycle
  • hot water pipes make a creaking sound
  • there is a sudden surge of water when a faucet is first turned on, then the pressure drops 
  • premature failure of water heaters, plumbing and fixtures 
  • hot water in the cold water lines

It’s important to know that the water heater relief valve should not be used as a means of controlling thermal expansion. Instead, contact a plumbing professional if you suspect a problem. The plumber can schedule an inspection and install proper thermal expansion control methods.

Contact Angel Goike at the Cross Connection office, (931) 553-2489, for more information.

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What is Cross-Connection?

Any physical or potential connection whereby the public water supply is connected with any other water system, whether private or public, either inside or outside any building or buildings, in such a manner that flow of water into the public water supply is possible through the manipulation of valves or because of ineffective check of back pressure valves, or because of any other arrangement. This means any pipe, valve, fixture, etc. in a drinking water plumbing system that may allow the drinking water within the system to become contaminated or questionable in quality.

How can backflow be prevented?

Some of the most harmful threats resulting in a backflow come from swimming pools, lawn irrigation systems and garden hoses. Through these devices a vacuum can be created and water can accidentally flow backwards or backflow carrying any chemical, cleaner or other contaminant directly back into our drinking water supply. Even a simple garden hose submerged into a pool, a bucket of water or other container filled with liquid can create a vacuum. However, there are a few simple preventative steps to follow around your home to avoid backflows.

Backflow prevention steps:

  • Never submerge the end of a garden hose in a bucket, pool, tub, sink, fertilizer or herbicide sprayer, ponds, etc. Always maintain an air gap between the liquid and the end of the hose.
  • Install vacuum bibs on outside faucets that will break a vacuum at the faucet. If a vacuum is created on the public water main line, it will be broken at your outlet and no water will be allowed to flow backwards. These devices are available in most hardware stores.
  • Install an approved backflow prevention device (BPD) by a certified backflow technician on all lawn irrigation systems. It is required by City code.

What is a backflow prevention device (backflow preventer)?

Backflow preventers are mechanical plumbing devices installed in a plumbing system to prevent water from flowing backward in the system. A properly installed, tested and maintained backflow preventer can reliably prevent the backflow of water of an unknown quality from flowing back into the public water system.

The installation and maintenance of backflow prevention devices shall be at the expense of the owner or occupant of the premises. If you don’t know if you need a backflow prevention device or if your water supply is protected, call the Cross Connection Control Office at 931.553.2489 for more information.


Please remember to winterize your backflow preventer to protect it from freezing temperatures. A damaged backflow preventer cannot do its important job of preventing water from traveling backwards into your water system or even possibly allowing contaminated water to enter the City’s safe drinking water supply.

Costly repairs and inspection fees for damaged backflow devices are the owner’s financial responsibility.

Backflow preventers are required on all water meters at commercial businesses, some home businesses and all residential irrigation systems. Call the cross connection office, 931.553.2489, for help locating your device.

Backflow Prevention Ordinance 

Cross Connection Plan

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Last updated: 6/29/2017 9:34:59 AM