FAQ: Backflow Prevention
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What is a cross-connection?
A cross-connection is an actual or potential connection between the public or consumer’s potable (drinking) water system and any non-potable source or substance. This connection presents a hazard to the quality of the public or the consumer’s drinking water system. Cross-connections are managed to prevent backflow incidents and to protect public safety.
What is backflow?
Typically, water will flow from the public water supply to the consumer’s plumbing distribution system. Backflow is the undesirable reversal of this flow of water and substances, with flow occurring instead from the non-potable source to the potable source.
Are all backflow incidents the same?
No. Cross-connections are generally classified as high or low hazard depending on the non-potable source or what the substance is. Each state (and sometimes the local public water utility) defines for itself the criteria for the hazards since there is no consensus or national standard for differentiating between a high and low hazard. There is some commonality among the definitions:
- A high hazard may be referred to as a toxic, health or contamination hazard where a backflow incident may pose a serious threat to the public water supply.
- A low hazard is any non-health hazard that is considered aesthetically objectionable or a pollutant that will not have serious effects.
What causes backflow incidents to occur?
Backflow incidents are caused by back pressure or back siphonage.
- Back pressure is created when the pressure within the customer’s system becomes greater than the water supply pressure. Elevated tanks, heating systems and booster pumps are some of the main causes of back pressure.
- Back siphonage is created when there is a negative or reduced pressure in the water supply main. Water main breaks or hydrant flushing are two of the main causes of back siphonage.
How are cross-connections protected to prevent backflow incidents?
Cross-connections are protected through containment or isolation. An effective control program ideally has a mix of containment and isolation protection.
- Containment is cross-connection protection at the consumer’s water service or meter. This protection contains the entire facility and protects the public water supply from the consumer’s plumbing system. It does not provide cross-connection protection within the facility.
- Isolation is cross-connection protection within the water consumer’s facility. This protection isolates the hazard at the point of use and protects the facility from contamination or pollutant hazards entering the internal plumbing system.
The Town of Hillsborough, like most municipalities, uses the containment method for its system.
Who is required to install a backflow prevention device?
Several types of facilities are required to install a backflow prevention device, including:
- Auto repair shops
- Barber shops and beauty salons
- Buildings that reuse or recycle water
- Buildings with commercial or public kitchens
- Buildings with groundwater wells
- Buildings with multiple water service lines
- Buildings with roof tanks and elevated storage lines
- Buildings with water-cooled equipment or chillers
- Commercial car washes
- Dye plants
- Food preparation facilities
- Food processing plants and meat or fish packers
- Funeral parlors
- Metal plating, cleaning, processing or fabricating facilities
- Hospitals, clinics and laboratories (including veterinary hospitals)
- Ice manufacturing facilities
- Large residential dwellings with water boilers that use rust-inhibitors or other water treatment chemicals (treated water boilers)
- Laundries and dry cleaners
- Medical and dental offices
- Morgues, mortuaries and autopsy facilities
- Nursing homes
- Paper processors
- Photo-processing facilities
- Printing facilities
- Properties with in-ground irrigation sprinklers
- Schools and colleges
- Sewage treatment plants or handling facilities
- Slaughterhouses and live poultry processing facilities
- Warehouses with toxic chemical storage
If your property or business type is not included in the above list and you have a specific question about your legal requirements, please call the town at 919-732-9459.
Can anyone test a backflow prevention assembly?
No. Backflow prevention assemblies must be tested by qualified individuals who have obtained the proper certifications pertaining to cross-connection and backflow assembly testing procedures. The town provides a list of certified testers and a Backflow Prevention Assembly Test and Maintenance Report form that must be filled out and submitted to Hillsborough Utilities Infrastructure Protection Supervisor Troy Miller. Miller can be reached by email or at 919-732-9459.
What happens if a backflow prevention assembly fails a test?
If a backflow prevention assembly fails a test and does not meet standards, the assembly must be repaired. All repairs must be made within 10 days, and the certified tester must retest and submit a Backflow Prevention Assembly Test and Maintenance Report.
Who has responsibility for cross-connection control?
Everyone. The water utility, local plumbing authority, water consumers and all individuals performing backflow prevention assembly installation, testing and repairs have some level of responsibility for ensuring an effective cross-connection control program.
Water utility responsibilities:
- Developing an approved ordinance to govern the program in accordance with state cross-connection guidelines or regulations.
- Conducting on-site facility surveys to make the proper determination of hazard and the method of protection required.
- Documenting and maintaining all records pertaining to field surveys.
- Maintaining an accurate inventory of all backflow assemblies and, in some jurisdictions, backflow devices.
- Developing a testing schedule of all testable backflow assemblies.
- Notifying the water consumer when assemblies are due for testing.
- Retaining all assembly test reports.
- Conducting enforcement action for noncompliance.
Local plumbing authority responsibilities:
- Implementing and enforcing local plumbing codes.
Water consumer responsibilities:
The water consumer is responsible for preventing unprotected cross-connections and maintaining protected cross-connections within the water consumer’s facility. This includes:
- Maintaining backflow devices that ensure cross-connections do not pose a risk to the water distribution system.
- Ensuring backflow assemblies are tested and maintained according to the testing schedule of the water provider by hiring qualified personnel in accordance with the local jurisdiction’s criteria.
Responsibilities of individuals involved with backflow assemblies:
The individuals performing backflow prevention assembly installation, testing and repairs are responsible for following all codes and regulations as outlined by the local cross-connection control program. This includes:
- Holding all necessary and required credentials to properly install, test and maintain backflow assemblies.
- Ensuring backflow assembly testing equipment is calibrated and working properly.
- Testing backflow assemblies in accordance with the proper testing procedures.
- Repairing backflow assemblies in accordance with manufacturers’ authorized repair procedures.
- Properly identifying and documenting all backflow assembly information, such as hazard, size, make, model, serial number and location.
- Documenting the results of backflow assembly tests.
- Submitting test reports to the water utility within the required time frame.
- Providing to the water consumer a copy of the test results.
Do backflow contamination incidents really happen?
Yes. For documented examples of contamination cases, see the University of Florida Training, Research and Education for Environmental Occupations’ website.