Your system has spent considerable money to ensure that all water it produces meets federal drinking water requirements. However, are you sure once this water has been produced that it is not later contaminated in the distribution system with water, liquids, gases, or corrosive products from external sources?
What can happen in a cross connection?
A real-life story excerpted from EPA’s Cross-Connection Control Manual [1]: In January 1981, a fast-food restaurant in the southeastern United States complained to the water department that all of their soft drinks were being rejected by their customers as tasting “salty.” This included soda fountain beverages, coffee, orange juice, etc. An investigation revealed that an adjacent water customer complained of salty water occurring simultaneously with the restaurant incident. This second complaint came from a waterfront ship-repair facility that was also being served by the same water main lateral. The investigation centered on the ship-repair facility and revealed the following:
With the potable priming line left open and the pumps maintaining pressure in the fire lines, raw salt water was pumped through the priming lines, through the spool sleeve piece, to the ship repair facility and the restaurant. |
Cross-connections are actual or potential connections between a potable water supply and a non-potable source, where it is possible for a contaminant to enter the drinking water supply. Almost every water user in the distribution system may have actual or potential hazards. For most residential customers, the misuse of an ordinary garden hose can become a cross-connection. Larger commercial and industrial customers, such as hospitals, funeral homes, or food-processing facilities, can have extensive internal water systems where a variety of drinking water contaminants, such as hazardous chemicals, radioactive materials or waterborne pathogens, can enter the potable water source. The contaminant can enter the potable water system when the pressure of the contaminated source exceeds the pressure of the potable source. This action is typically called backsiphonage or backflow.
As a water supplier, you have the primary responsibility to protect the water supply for all of your customers. Therefore, cross-connection control programs may require backflow-prevention assemblies within private water systems as well as backflow-prevention devices installed at water service connections or meters.
The elements of a good cross-connection control program should include:
- establishing an adequate legal authority by the water purveyor
- training of water-utility personnel and others involved in protecting the water supply
- education of the water consumer/customer
- establishing standards and specifications of water-supply protection devices and a means of approving of them
- compiling an inventory of existing health hazard facilities and setting up an inspection program
- installing, testing and maintaining backflow-prevention devices
- surveying and retrofitting existing facilities and the discovery of undesirable plumbing practices
- documentation and recordkeeping
What should public water supply systems be doing now?
- Survey your system’s users for actual or potential contamination or hazards within the system.
- Inspect new water services and existing services where health hazards are suspected.
- Require water users to properly install, maintain, inspect and test cross-connection control assemblies when actual or potential contamination hazards exist.
- Require annual inspections and testing of mechanical assemblies in health hazard service.
- Require water users to notify the water system about existing hazards or changes that may affect the degree of hazard classification.
- Develop and maintain a record system regarding cross-connection hazards, controls, mechanical devices, and your inspection and testing program.
Additional information on cross-connection control [2]
Example of a cross-connection control manual [3]