James City Service
119 Tewning Rd.
Williamsburg, VA 23188
Hours of Operation
Engineering & Operations
7 a.m.-3:30 p.m.
8 a.m.-4:30 p.m.
For questions about:
Starting or Stopping Service
Web Self-Service or Kubra
Water, Sewer or Grinder Pump Service Questions
7 a.m. to 3:30 p.m.
Water / Sewer Emergencies
7 a.m. to 3:30 p.m
Special Information Hotline
Dial 811 in Virginia or
- Landlord Authorization Form
- Leak Adjustment Request
- Utility Service Connection - Apply for new water connections online
- 60 Day Exemption Form
- JCSA Forms
Backflow Prevention Frequently Asked Questions (FAQs) - Continued
6. Why do water system operators need to control backflow? Backflow into a public water system can pollute or contaminate the water in that system (i.e., backflow into a public water system can make the water in that system unusable or unsafe to drink), and each water supplier has a responsibility to provide water that is safe to drink under all foreseeable circumstances. Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink. For these reasons, each water supplier must take reasonable precautions to protect its public water system against backflow.
7. Are all residential homes required to have backflow assemblies? At this time only those residential homes that have irrigation and sprinkler systems are required to have backflow assemblies on those systems.
8. Why are irrigation systems considered to be hazardous to the water system? Irrigation systems include but are not limited to agricultural, residential, and commercial applications. The Virginia Department of Health classifies lawn sprinkler systems and irrigation systems as a high hazard for several reasons. Sprinklers, bubbler outlets, emitters, and other equipment are exposed to substances such as fertilizers, fecal material from pets or other animals, pesticides, and other chemical and biological contaminants. Sprinklers may remain submerged under water after use or storms. Should the water system pressure suddenly decrease, such as in the case of a water main break, line flushing, or during a major fire involving multiple fire hydrants, these harmful substances can be back-siphoned into the water distribution system. They may be subject to various onsite conditions such as additional water supplies, chemical injection, booster pumps, and elevation changes. All of these conditions must be considered when determining backflow protection. Some hazards relating to irrigation systems are:
- Fertilizers: Ammonia salts, ammonia gas, phosphates, potassium salts.
- Herbicides: 2,4-D, dinitrophenol, 2,4,5-T, T-pentachlorophenol, sodium chlorate, borax, sodium arsenate, methyl bromide.
- Pesticides: TDE, BHC, lindane, TEPP, parathion, malathion, nicotine, MH, and others.
- Fecal matter: Animal (domestic and non-domestic).
9. What type of backflow prevention assemblies are allowed in irrigation systems? For those irrigation systems connected to the JCSA potable water system, the appropriate protection is a Reduced Pressure Principle (RP) backflow prevention assembly. A Pressure Vacuum Breaker (PVB) may be used for service protection if the JCSA potable water service is the sole source of supply to the premises or property, if it is used strictly for irrigation, and there is no means or potential for backpressure (IE: PVB’s protect against backsiphonage only). Any irrigation system that has a means to introduce chemicals into the JCSA potable water system shall always be protected against backflow by a RP backflow preventer.
Approved backflow prevention devices and assemblies are those that meet AWWA standards, and are approved by ASSE and the USC-FCCC (University of Southern California Foundation for Cross Connection Control and Hydraulic Research).
*** Please note that Double Check Valve Assemblies (DCVA) are not allowed in irrigation systems. Irrigation systems are considered as a “high hazard” and therefore are not allowed to use a DCVA.
10. How do I know if I have a backflow prevention assembly? Generally, the backflow prevention assembly is normally located as close as possible to the water service connection, but must remain on private property. It is usually installed outdoors and in a “loop” of your irrigation system that extends above the ground. (See pictures below)
11. Is there a minimum height that the backflow assembly must be installed? Yes. Backflow prevention assemblies should be installed in accordance with the manufacturer’s installation instructions, the Uniform Statewide Building Code and any additional instructions offered by the JCSA. Regulations regarding flow orientation and proper access to the backflow preventer should also be followed (see the JCSA Backflow Prevention and Cross Connection Control Plan for further guidance).
At a minimum the following guidelines should be followed:
Must be installed at least 12 inches above all downstream piping in the system. (The height of pop up sprinkler heads should be included in this requirement)
The height should not exceed 60 inches and the assembly should be accessible for testing and servicing.
The assembly should be properly supported.
No chemicals allowed
Shall be installed a 12 to 36 inches above grade and not subject to flooding or submersion.
The assembly should be properly supported and accessible for testing and servicing.
Must be used if chemicals will be introduced in the irrigation system.
***Note: Customers should take necessary actions to ensure that their backflow prevention assembly does not get damaged during freezing temperatures.
Properly installed RP Assembly
Properly installed PVB Assembly
RP installed too close to the ground
PVB installed too low
12. How often do I have to have my backflow assembly tested? They must be tested at least annually. Backflow assemblies are mechanical assemblies and as such they are subject to fail, which is why the VDH requires that they be tested at least once a year. In addition, newly installed backflow assemblies and backflow assemblies that are repaired or relocated must also be tested. This requirement is echoed by Virginia Maintenance Code, International Plumbing Code, and the Environmental Protection Agency’s Cross Connection Control Manual.
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