Backflow Information
Cross Connection Control Program/Backflow Prevention
Important Forms:
MPW Backflow Assembly Test Report
MPW Annual Testing Agreement
MPW Cross Connection Control Manual
SCDHEC TESTERS: http://www.scdhec.gov/environment/water/docs/bfgen.pdf
Attention Irrigation Customers!
On June 13, 2000, the S.C. Dept. of Health and Environmental Control required all new residential irrigation meters be protected with a backflow prevention assembly. The MPW Commission amended the Backflow Prevention Guidelines to also include meters installed before this date. If you have an irrigation system that is tied to the public water supply, your irrigation meter must have a backflow preventor to protect the MPW water system from potential contamination.*
* Under certain conditions, pesticides, herbicides, and other contaminates may enter your irrigation system, which if not properly isolated by a backflow assembly, could then enter the public water supply.
Installation Requirements
- Only Reduced Pressure Principle (RP) backflow assemblies are allowed on irrigation systems.
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Backflow assemblies must be installed 12 inches above ground.Backflow assemblies must be located within 15 feet of the irrigation meter. Installations more than 15 feet must be approved by an MPW Inspector prior to installation.
Testing Requirements
- Backflow assemblies must be tested upon installation, after any repairs, and once each year.
- Backflow assemblies must be tested by a SCDHEC Certified Tester.
- Copy of testing results must be sent to Mount Pleasant Waterworks.
Recommendations
- Backflow assemblies should be protected from freezing. Installing an insulated enclosure over the assembly or turning the water off at the meter and draining the assembly in freezing weather is recommended.
- Wrapping the assembly with installation is not recommended because it will prevent access to test cocks, check valves and relief valve.
- There are several types of covers you can get from irrigation and landscape supply stores that will provide freezing weather protection.
ACTION STEPS to help get you started:
- Installation — The backflow assembly may be installed by a South Carolina Department of Health and Environmental Control (SCDHEC) Certified Tester, irrigation contractor, or by the customer.
- Testing — The backflow assembly must be tested by a SCDHEC Certified Tester (see link at top of page). Your irrigation contractor may be a Certified Tester. Get the Backflow Test Form that must be completed by the tester, and a copy of the Backflow Contract Agreement.
- Submit Test Results to MPW — Send the test results to the attention of Backflow Prevention Manager Del Harbin at Mount Pleasant Waterworks, PO Box 330, Mount Pleasant, SC 29465-0330.What is a Cross-Connection?Customers use water for many different purposes, and the water may come in contact with other substances not fit for consumption. This connection between clean water and other substances is called a “cross-connection.”
How could the water in the customers’ plumbing system flow back into the public water supply?
MPW may have to shut off a water main in isolated areas to make repairs. This may cause a drop in water pressure, allowing water inside a customer’s plumbing to flow back into the public water system due to gravity. Sometimes customers will have pumps downstream from the water meter which could inadvertently pump water back into the public water system. These are just two examples of “backflow”.
How can backflow be prevented?
Backflow can be prevented by installing a backflow preventer. This a device that is installed on a water service that will only allow water to travel in one direction—from the public water supply to the customer.
MPW's Backflow/Cross-Connection Control Program
Mount Pleasant Waterworks initiated a Cross-Connection Control Program In accordance with regulations from the South Carolina Department of Health and Environmental Control (SCDHEC). The program was initiated to safeguard public drinking water supply by preventing the water in a customer’s plumbing system from flowing back into the public water supply. The Commission requires all irrigation systems be fitted with a reduced pressure (RP) backflow prevention device (see diagram below). In addition:
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MPW inspects all businesses that sign up for service to determine if the installation of a backflow device will be required and if so, ensure that a secure, sufficient device is installed.
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MPW installs dual-check backflow devices (non testable) on all residential home meters. [MPW has retro-fitted all residential meters installed before 1987 with dual-check backflow devices.]
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MPW requires all customer with irrigation systems or fire sprinkler systems to install a Reduced Pressure (RP) backflow device (testable).
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MPW maintains records on all testable backflow devices to ensure they are tested annually and repaired when required.
What to look for —and how to fix— potential areas around your home that could be the source of cross-connections:
POTENTIAL PROBLEM: water hose that is attached to fertilizer, pesticide or herbicide sprayers could contaminate your water supply You can reduce the risk of contamination through this type of cross-connection by shutting off the water supply to the hose at the faucet when you are finished. Even if the hose has a valve on the nozzle attachment, any decrease in water pressure could siphon the water from the hose — or the sprayer — back into your plumbing system.
FIX: Purchase a hose bib vacuum breaker, available from any hardware store, that will prevent back-siphonage.
POTENTIAL PROBLEM: A hose left in a bucket used for cleaning.
FIX: Remove the hose from the bucket (or sink) and shut off the water at the tap.
POTENTIAL PROBLEM: Underground irrigation systems are one of the types of cross connections posing a health hazard to the public drinking water system.
Contamination from herbicides, pesticides and animal droppings can enter your irrigation system when below ground sprinkler heads are used.
FIX: Installation of a reduced pressure (RP) backflow prevention device (example below). (Note: The Commission requires all irrigation systems be fitted with an RP device to prevent contaminated water from flowing back into the public water supply.)
