Backflow Prevention

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Contact

Casey Schoals
Water Construction Inspector/Backflow Specialist

Phone: 770-641-3707
Email Backflow Prevention

Hours & Location

Monday - Friday
7:00 AM - 4:00 PM

105 Frank Lewis Drive
Roswell, GA 30075

Overview

The City of Roswell has developed a Backflow Prevention Program to comply with Federal and State laws regarding safe drinking water. The purpose of this program is to prevent the introduction of contaminants or pollutants into the potable water system. The program applies to all commercial and residential customers of the City of Roswell's Water Utility.

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What is Backflow

Backflow is the undesirable reversal of flow of a liquid, gas, or other substance in a potable water distribution piping system as a result of a cross connection. Backflow contamination of a public water system by contaminants and pollutants through uncontrolled cross connections could occur as a result of the reversal of flows brought about by fluctuations in water pressure within the water system (i.e. main break, fire fighting, etc.).

The requirements for the level of protection are based on the following criteria:

High Hazard: A facility considered as a possible source of contaminates. Contaminates are toxic substances or those creating a health hazard due to the nature of the product. This category would include multi family dwellings, hospitals, doctors, dentists offices, metal plating operations, chemical companies, facilities that have the capabilities of exerting back pressure on their water tap and other industrial businesses using toxic substances. These operations would be required to install a reduced pressure principle backflow prevention assembly (RPZ) for maximum protection.
Medium Hazard: A facility considered as a possible source of pollutants. Pollutants are substances considered to be objectionable in nature such as those causing discoloration, odor, or taste in water. This category would include commercial businesses such as grocery stores, restaurants, day care centers, office buildings, and any business that has an auxiliary water supply. Automatic sprinkler systems would also apply to this category. These operations would require and double check backflow prevention assembly (DCV) for their required degree of protection.
Low Hazard: Considered to be the least likely to be a source of contaminant or pollutant. Typically this would include only a single or duplex family dwelling served by a single water meter. The City of Roswell’s Water Utility has installed dual check valves at the meter.

For questions the City of Roswell's Backflow Prevention Program, please contact us at backflowtest@roswellgov.com or 770-641-3707.

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What is Thermal Expansion

When water is heated and stored in a distribution system or a branch of the system that has been closed by the installation of a backflow prevention device or any other checking device, an approved auxiliary relief valve, or expansion chamber should be installed to limit thermal expansion of the water being heated to not more than 80 PSI no-flow pressure at any fixture on the system. The installation of such a device shall be in accordance with State Plumbing Code (Section 1112.8) and shall be the responsibility of the customer.

It is the customer's responsibility to determine whether thermal expansion is a possibility. City of Roswell is not responsible for damages occurring within the customer's water system.

More information regarding Thermal Expansion

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Backflow Specifications

Backflow specification and details for backflow prevention devices for various sizes:

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FAQs

Are there any regulations in OSHA regarding cross connections?

Yes, OSHA requires that no cross connection be allowed in an installation unless it is properly protected with an approved backflow preventer. These requirements are covered in the B.O.C.A, Uniform Plumbing Code, and City, State, and Federal regulations.
Where is a reduced pressure zone backflow preventer (RPZ) used?

An RPZ may be used on all direct connections to the potable water supply which may be subject to back pressure or back-siphonage, and where there is the possibility of contamination by the material that constitutes as a potential health hazard.
Where is a double check backflow prevention assembly used?

A double check backflow prevention assembly may be used as protection of all direct connections through which foreign materials might enter the potable water system in concentration which would constitute a nuisance or aesthetically objectionable, such as air, steam, food, or other material which does not constitute a health hazard.
What are the 5 basic products used for backflow protection of cross connections?
1. Air Gap
2. Atmospheric Vacuum Breakers
3. Pressure Vacuum Breakers
4. Double Check Valve Assembly
5. Reduced Pressure Zone Backflow Preventers
What is the difference between a toxic and non-toxic substance?

A toxic substance is any liquid, solid, or gas, which when introduced into a water supply creates, or may create, a danger to health and well-being of the consumer. An example is treated water boiler. A non-toxic substance is any substance that may cause a non-health hazard, is a nuisance or is aesthetically objectionable. For example, food stuff such as sugar, soda, etc.
What is meant by degree of hazard?

The degree of hazard is a commonly used phrase utilized in cross connection programs (backflow prevention programs) and is simply a determination of whether the substance in the non-potable water supply is toxic or non-toxic.
What is the difference between pollution and contamination?

Pollution of a water supply does not constitute as an actual health hazard, although the quality of the water is impaired with respect to taste, odor, and color. Contamination of a water supply, however, does constitute as a health hazard; the consumer being subjected to potentially lethal water borne disease or illness.
What protection is required for sill cocks?

A hose bibb vacuum breaker should be installed on every sill cock to isolate garden hose applications thus protecting the potable water supply from contamination.
What is potentially dangerous about an unprotected sill cock?

The purpose of a sill cock is to permit easy attachment of a hose for outside watering purposes. However a garden hose can be extremely hazardous because they are left submerged in swimming pools, lay in elevated locations (above the sill cock) watering shrubs, chemical sprayers are attached to hoses for weed killing, etc.; and hoses are often left laying on the ground which may be contaminated with fertilizer, cesspools, and garden chemicals.
What is potentially dangerous about an unprotected sill cock?

The purpose of a sill cock is to permit easy attachment of a hose for outside watering purposes. However a garden hose can be extremely hazardous because they are left submerged in swimming pools, lay in elevated locations (above the sill cock) watering shrubs, chemical sprayers are attached to hoses for weed killing, etc.; and hoses are often left laying on the ground which may be contaminated with fertilizer, cesspools, and garden chemicals.
What is the most common form of a cross connection?

The garden hose is the most common form of a cross connection. It can be easily connected to the potable water supply and used for a variety of potentially dangerous applications.
What is a cross connection?

A cross connection is a direct arrangement of piping line which allows the potable water supply to be connected to a line which contains a contaminant and/ or pollutant. An example is the common garden hose attached to a sill cock with the end of the hose lying in a cesspool. Other examples are a garden hose attached to a service sink with the end of the hose submerged in a tub full of detergent, supply lines connected to bottom-fed tanks, supply lines to boilers, supply lines to automatic irrigation systems.
What factors can cause a back pressure backflow condition?

Back pressure-backflow is created whenever the downstream pressure exceeds the supply pressure which is possible in installations such as heating systems, elevated tanks, and pressure producing systems. An example would be a hot water space-heating boiler operating at 15- 20 lbs pressure coincidental with the reduction of the city supply below such pressure (or higher in commercial boilers). As water tends to flow in the direction of least resistance, a back pressure- backflow condition would be created and the contaminated boiler water would flow back into the public drinking water supply.
What is back pressure?

Back pressure backflow is the reversal of normal flow in a system due to an increase in the downstream pressure above that of the supply pressure.
What factors can cause back-siphonage?

Back-siphonage can be created when there is a stoppage of the water supply due to nearby fire-fighting, repairs or breaks in the city water mains, etc. The effect is similar to the sipping of an ice cream soda by inhaling through a straw which induces the flow in the opposite direction.
What is back-siphonage?

Back-siphonage is the reversal of normal flow in a system caused by the negative pressure (vacuum or partial vacuum) in the supply piping.
What is Backflow?

Backflow is the undesirable reversal of flow of a liquid, gas, or other substance in a potable water distribution piping system as a result of a cross-connection due to back-siphonage or back pressure.

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