Cross-Connections

Gary Carlson

Drinking Water Program

U.S. EPA Region 8

Cross-Connections

• Plumbing Cross Connections- defined as actual or potential connections between a potable and non-potable water supply

- constitute a serious public health hazard

- have been responsible for contamination of drinking water, and have resulted in the spread of disease

Cross-Connections

• Plumbing cross-connections are a dynamic problem because piping systems are continually being installed, altered or extended

• Control of plumbing cross-connections is possible through thorough knowledge and vigilance

Cross-Connections

• Education is essential even for those experienced in piping installations - failure to recognize cross-connections and dangers

Cross-Connections

• All municipalities with public water supply systems should have cross-connection control programs.

- Required by some regulators• Institutional and private water supplies

should also be familiar with the dangers of cross-connections and should exercise careful surveillance of their systems

Cross-Connections• Cross-connections are the links through

which it is possible for contaminating materials to enter a potable water supply

• Contaminants enter the potable water system when the pressure of the polluted source exceeds the pressure of the potable source

- backsiphonage

- backflow

Cross-Connections

• Cross-connections may appear in many subtle forms and in unsuspected places

• The probability is great of contamination of a drinking water through a cross-connection within a single plumbing system

Cross-Connections

Problems:- plumbing is frequently installed by persons who are unaware of the inherent dangers of cross-connections

- connections are made as a simple matter of convenience without regard to the dangerous situation that might be created:

fire protection sprinkler systems

lawn irrigation systems

hose bibs

Cross-Connections

• Plumbing installers must know that hydraulic and pollution factors may combine to produce a sanitary hazard if a cross-connection is present.

• Plumbing installers and others must realize that there are available reliable and simple standard backflow prevention devices and methods that can be substituted for dangerous direct connection.

Cross-Connections

• Hazards resulting from direct connections greatly outweigh the convenience gained.

Cross-Connections

• Backflow- reversed flow due to backpressure other than siphonic action

- any interconnected fluid systems in which the pressure of one exceeds the pressure of the other may have flow from one to the other as a result of the pressure differential

- flow occurs from the zone of higher pressure to the zone of lower pressure

Cross-Connections

• Backflow and back-siphonage prevention

- one method to avoid certain types of backflow is to totally separate the systems

Cross-Connections• Install mechanical devices

- air gap

- barometric loops

- vacuum breakers - both atmospheric and pressure

- double check with intermediate atmospheric vent

- double check valve assemblies

- reduced pressure principle devices

Cross-Connections• Backflow devices must be inspected and

tested by certified technicians.

• Under the provisions of the Safe Drinking Water Act of 1974 and subsequent Amendments, the water purveyor is held responsible for providing water that meets all applicable National Primary Drinking Water Standards