Water Supply Institutions

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Water Supply Institutions
CALIFORNIA
GLOBAL
USA
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Water Provision

• Water is a classic public good a basic
  necessity for life, health and welfare.
• Water service has been used as a tool for
  economic growth, and in some places as a tool
  against urban expansion.
• Water has usually been managed and protected by
  public agencies, or very highly regulated private
  entities.
• Some kind of public utilities commission or
  public ombudsman usually determines acceptable
  tariffs and overlooks service performance.

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Municipal Water Systems

• As populations have grown, they have generally
  turned away from individual water supplies to
  collective water systems.
• Water supply institutions were historically
  concerned with the basic act of providing water
  moving it from A to B and then distributing it.
• They were little concerned with what happened to
  it afterwards (wastewater) or what impacts
  resulted to the environment from the way they
  provided it.
• They did little to promote conservation and
  efficiency of use.
• This is no longer a paradigm that works in many
  regions (see histories of LADWP, Lincoln NE New
  York City in Cech p117-125).

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Evolution

• Water utilities frequently change drastically and
  grow over time with the expansion of their client
  base.
• As communities spread out, then so do
  distribution systems, adding main lines and
  satellite distribution networks to serve distinct
  demand centers.
• Due to differential development and growth of
  communities in a given area, very complex
  patterns of water provision can result.
• Frequently, water systems will grow out from
  previously distant nuclei such that neighboring
  communities may end up with distinctly different
  sources and providers (e.g. Walnut Creek and
  Concord).
• Similarly, distant smaller communities that grow
  up along the route of a larger, older communitys
  aqueduct system may be serviced by that system
  through connections to it.

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Water Providers

• The fundamental purpose of water supply
  institutions in the modern era is not just to
  bring water but is generally stated as being
• to provide an adequate water (and wastewater)
  service to water users so that they can realize
  their economic, social and environmental goals in
  an efficient manner.

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Types of Water Providers

• There are many types of public and private water
  supply institutions municipal utilities, water
  districts, service districts, irrigation
  districts, service companies, etc.
• For example, there are more than 40 different
  California statutes under which public water
  institutions may be legally incorporated and
  organized with the powers and authority to
  distribute water.
• In some cases, water is provided by city
  governments or for-profit companies.

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Service Territories and Responsibilities

• Most water agencies, public and private
• monopolistically serve a fixed service area
• develop new infrastructure
• own and operate physical assets
• finance capital improvement
• charge fees and levy taxes
• provide customer service and education
• comply with all regulations
• participate in the broader planning process

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The Commerce of Water Supply

• Water supply institutions can be retailers,
  wholesalers or both.
• Retailers sell water directly to the general
  public.
• Wholesalers sell water to other providers who in
  turn sell it to their own customers.
• e.g. The City and County of San Francisco is both
  retailer and wholesaler.

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City and County of San Francisco and its
Wholesale Customers (Bay Area Water Users
Association)
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Revenue Generation

• In North America, most water providers are public
  agencies but in France England they are all
  private companies.
• In both cases, providers are allowed to cover
  their costs with standing charges, one-off fees
  (hook-up fees, special assessments, etc.) and
  commodity tariffs.
• Allowable expenses and profits are usually highly
  regulated by governments.
• Domestic tariff structures for LADWP, Lincoln NE
  and New York City are summarized in Cech (p120,
  122, 129).
• Most providers are moving to metered bills with
  inclining rates like LA and Lincoln.

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Water Service Functions

• Unlike many other industries (except perhaps gas
  and electric), water providers are often expected
  to try and limit the demand for their product
  through conservation and waste prevention.
• Many must provide free or subsidized service to
  the poor and to certain public sector users
  so-called lifeline rates.
• Many water providers also provide sewage
  collection and waste treatment services.
• If they dont actually provide the services, they
  may bill on behalf of sewer operators (e.g.
  cities) and wastewater treatment operators (e.g.
  sanitary districts).

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Water Supply Infrastructure

• How does our water get to us from the source?
• What steps and technologies are employed?
• What are the key infrastructure elements in our
  system?

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Water Supply Infrastructure

• Water supply infrastructure must supply water to
  consumers reliably i.e. in sufficient quantity
  and at the correct times and locations to meet
  their needs.
• It must also maintain key service characteristics
  which include water pressure, purity, taste,
  smell, color and temperature.
• Reliability encompasses both constancy of service
  i.e. no outages due to pipe breakage or other
  problems (in California this would include due to
  droughts) and consistency in service quality
  (e.g. no abrupt variations in pressure).
• Constancy of service must plan for and deal with
  extreme hazard contingencies such as earthquakes,
  fires and floods (and now even terrorism).

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Water Supply Hydraulics

• Distribution systems are usually designed to use
  the force of gravity to a maximum, as it has
  since the earliest of times (e.g. the Roman
  aqueducts).
• Water treatment plants are usually located close
  to the highest elevation in a service district.
• Wastewater treatment plants are usually located
  close to the lowest elevation in a service
  district.
• Where significant topographic variation exists in
  a service district, separate water and wastewater
  treatment plants may have to be built to serve
  different demand-centers.
• Wastewater systems, which are mostly
  unpressurized, are more influenced by topographic
  variation.

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The Headworks

• The headworks are all the facilities that link
  the watershed and source to the distribution
  system.
• They may include various dams, reservoirs,
  intakes, canals, pumps, boreholes, aqueducts, and
  treatment plants.
• Each system has unique characteristics but uses
  standard technologies and may be added
  incrementally.
• LA has multiple headwork systems developed over a
  century and associated with different sources
  the LA Aqueduct system from the Owens Valley, a
  share of the Colorado River Aqueduct system, and
  a connection to the State Water Project.
• New York also has many headworks developed over
  a prolonged period the Croton system in
  Westchester Co., the distant upstate Catskills
  systems, finally back closer from the Delaware
  Basin.
• Lincoln NE, on the other hand, has a single
  headworks system a field of wells on the Platte
  River alluvium and 25 mile pipeline this
  replaced an inferior source.

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The Headworks of the City and County of San
Francisco
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Distribution Systems

• Distribution systems are generally complex
  networks with many cross-connections and valves
  that allow different segments to be individually
  isolated for repairs, etc.
• Distribution networks look like the road networks
  under which they run, with few dead-ends and lots
  of junctions.
• Distribution lines, if not underlying public
  right of ways, are granted easements and
  providers have access rights across private
  property.
• A customers responsibility for the water pipes
  normally begins at his/her side of the water
  meter.

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The Distribution Network

• Aqueducts (canals and pipes) can be huge e.g.
  EBMUD has 3 parallel 7ft diameter pipes from the
  Sierra, NY City Tunnel No. 3 is 24ft in diameter,
  Londons ring main is 20ft across.
• They may lie on the surface or pass deep
  undeground (e.g. City Tunnel No. 3 is over 400
  feet below ground in places)
• Within-city distribution pipes usually vary in
  size from two feet in diameter to 1/2 inch, and
  are a variety of materials, increasingly plastic.
• GIS systems are frequently used to manage
  distribution networks, with each section of pipe
  recorded in the database as to its character and
  location.

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Distribution Storage

• Few distribution systems can work on gravity
  alone and water will need to be lifted to storage
  reservoirs to provide local pressure.
• Each distribution network will require a
  particular configuration of storage reservoirs
  and lift pumps.
• Storage reservoirs are sized to meet peak demand
  and fire needs, provide back-up supply and
  maintain pressure and seldom contain more than 3
  days worth of water.
• In hilly terrain, water pressure can vary between
  20 psi and 200 psi depending on where one sits
  compared to the storage elevation - optimum
  pressure is 60-80 psi.
• Some providers charge a pressure differential
  if you live at a higher elevation, you pay a
  higher price (e.g. EBMUD).

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Distribution Losses

• Water losses occur in every network a good
  system will lose less than 5, bad ones, perhaps
  as much as 50 or more.
• They comprise physical losses (cracked or
  ruptured pipes, leaking pipe-joints, dripping or
  gushing taps and hydrants, broken valves and so
  forth).
• There are also non-physical losses (illegal
  connections, under-registering/broken meters,
  meter reading errors, and clerical billing
  errors).
• Deterioration of old fashioned materials unable
  to withstand high pressures or ground stresses
  leads to frequent breaks in old systems,
  necessitating large-scale rehabilitation projects.

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Wastewater System

• The distribution network is generally mirrored by
  a wastewater collection system connecting each
  users sewer pipe to a wastewater treatment
  plant.
• Most sewers use gravity flow and require larger
  diameter pipes so as to accommodate and conduct
  the more viscous fluid.
• Where sewers are absent, septic tanks and
  leachfield systems will be installed.
• In many developing nations, sewers, wastewater
  treatment and/or septic systems are absent.

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Wastewater Networks

• There is much less interconnectivity in a sewer
  network than a supply network.
• Many sewers are very large, particularly if they
  are combined stormwater and sewer pipes (you can
  walk down them).
• Agencies with combined sewers are being forced by
  legislation such as the US CWA to separate them
  and/or build wet weather retention and treatment
  systems to prevent plant overload and bypass
  during storms, when runoff rushes into sewers.

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Wastewater Reuse Systems

• There are increasing demands to use wastewater
  plant effluent for useful purposes instead of
  releasing it to a receiving body.
• Wastewater reuse depends on whether
  infrastructure is available to get it to
  potential users.
• Some nations/regions/municipalities have dual
  carriers (e.g. Israel, Irvine CA).
• Increasingly, new developments are being fitted
  with dual systems and selective pipelines are
  being installed to large users near wastewater
  plants.
• In America, such non-potable water carriers are
  color-coded purple.
• Retrofitting existing communities for widespread
  wastewater reuse will be very, perhaps
  prohibitively expensive.