United States
Environmental Protection
Agency
Distribution  Systems:
A  Best  Practices  Guide



Purpose
Target
Audience


This Guide discusses the importance of maintaining
your distribution system.
This Guide is intended for owners and operators of all public water systems
serving fewer than 10,000 persons.


Distribution Systems usually consist of:
* Piping and fittings * Pumps and pump stations *
» Storage tanks » Backflow prevention devices »
Meters
Hydrants and valves
                       A properly maintained distribution system is important for ensuring that you can: provide high
                       quality water to your customers, continue operating in the event of an emergency, help
                       minimize property damage as a result of responding to an emergency, and help prevent
                       contamination events. A properly maintained distribution system can also extend equipment
                       life-cycles and minimize problems related to minor or major equipment failures.
                        The following table provides suggested frequencies of routine and preventative maintenance
                        tasks for systems under normal operation.  However, anytime a system experiences water
                        quality issues, the appropriate tasks should be performed as frequently as needed. Contact
                        your state for more information.
                               Task
                           Valve exercising
                          Flushing pipelines
                            Storage tank
                            inspections
                                 Benefits
                      *   Improves reliability.
                      »   Familiarizes crews with valve
                         location.
                      »   Identifies inoperable valves.
                      »   Locates obstructed valve boxes.
                      »   Ensures isolation of distribution
                         system sections when necessary.
                      »   Removes aged water from the
                         pipeline.
                      »   Reduces buildup of biofilms and
                         sediments.
                      »   Restores disinfectant residual.
                         Detects vandalism.
                         Identifies defects.
                         Ensures that access hatches are
                         locked.
                         Ensures that vents, overflows, and
                         drains are screened.
Suggested Frequency
      Annually.
 Annually for all piping.
More often in areas with
  water quality issues
  (e.g., dead ends).
  Daily or weekly for
vandalism. Annually for
     other items.

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        Task
     Storage tank
     maintenance
 Routine water quality
 monitoring (e.g., pH,
     temperature)
Inspecting and flushing
  hydrants and valves
 Maintaining operating
  pressure range of
  distribution system
 Tracking unaccounted
      for water
Testing for presence of
    excess biofilms
 Monitoring corrosion
 Checking for normal
   wear (such as in
mechanical parts found
 in pumps and control
       valves)
          Benefits
Improves protection against
sources of contamination.

Extends the useful life of the
equipment.
Provides information on potential
contamination of raw and finished
water.

Helps determine effectiveness of
treatment.

Helps assure the compatibility of
the water with the materials.
Ensures that hydrants and valves
are operable and that no water
losses occur.

Ensures that hydrants and valves
are not susceptible to tampering.
Reduces the risk of backflow
contamination.

Helps your system provide better
service to customers.

Reduces damage to infrastructure
due to excess pressure.

Provides adequate fire  flow.
Can reduce pumping and treatment
costs.

Helps identify leaks, breaks, stolen
water, and inaccurate meters.
Indicates a presence of inadequate
chlorine residual, possible high
disinfection byproduct levels, and
water stagnation.
Identifies the need to modify
treatment or conduct flushing.
Can extend the useful life of
infrastructure components.

Helps avoid unnecessary
replacement or operational costs.
 Suggested Frequency
   Every 3 years for
 cleaning.  Painting and
 repairs as dictated by
      inspection.
Will vary depending on
water quality and state
      regulations.
Once or twice per year.
     Continuously.
  Daily at the source.
   Monthly or during
routine meter reading at
 customer connections.
 Monthly in conjunction
  with Total Coliform
       sampling.
       Annually.
   According to the
    manufacturer's
   recommendations.
 For additional information:
 Call the Safe Drinking Water Hotline at 1 -800-426-4791, visit the EPA Web site at
 www.epa.gov/safewater/smallsys.html, or contact your State drinking water representative.
 Office of Water
     September 2006
 EPA816-F-06-038

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