Cross-Connections

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Cross-Connections

• Gary Carlson
• Drinking Water Program
• U.S. EPA Region 8

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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

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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

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Cross-Connections

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

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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

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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

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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

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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

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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.

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Cross-Connections

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

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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

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Cross-Connections

• Backflow and back-siphonage prevention
• - one method to avoid certain types of backflow
  is to totally separate the systems

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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

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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