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Mexico City's Water Supply Improving the Outlook for Sustainability (1995) / Chapter Skim
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5 Water Quality and Health Concerns
Pages 39-52

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From page 39...
... Problems with land use include a large proportion of settlements without sewage collection, unlined drainage canals carrying untreated domestic sewage and industrial wastewater, unlined solid waste landfills, and poorly controlled storage and disposal of hazardous waste (Mazari and Mackay, 19931. The mountain zone is not urbanized to the same extent as zones of the lower elevations.
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From page 40...
... Many are located close to unlined drainage canals that contain untreated domestic and industrial wastewater. These abandoned wells may provide an alternate and more direct route for contamination of the water supply aquifer from the surface.
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From page 41...
... Pesticide residues have been detected in human adipose tissue in samples from the Mexico City population (Albert et al., 1980~. Human exposure to pesticides occurs more readily through direct consumption of agricultural products or by runoff from agricultural fields that may contaminate surface waters used as drinking water sources (National Research Council, 19931.
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From page 42...
... The most basic sampling is called Level A which is used to detect bacteriological contamination and to yield information regarding free chlorine residuals, acidity, electronic conductivity, temperature, and turbidity. Level 2A additionally samples minimum physical and chemical characteristics prevalent in the Federal District and include total alkalinity, chlorides, color, oxygen demand, total hardness, and ammonia nitrogen.
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From page 43...
... Copper Cyanide Fluoride Iron Lead Magnesium Hardness, as CaCO3 Manganese Mercury Nitrates, as N Nitrites, as N Selenium Sulfate Total Alkalinity, as CaCO3 Zinc Carbon-ChlorofoM~ Extractables Carbon-Alcohol Extractables Organic Nitrogen, as N Phenols Color, Pt-Co Units Free Chlorine (overdosed water) Methylene Blue Active Substances pH Taste and Odor Turbidity, NTU (silica scale)
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From page 44...
... The Federal District's Central Control Laboratory at Xotepingo has identified and mapped additional ground water parameters that indicate the potential for organic and/or biological contamination. As of 1993, testing at the well head revealed areas of non-compliance with color, total solids, ammonia, organic nitrogen, nitrates, chemical oxygen demand, and hardness.
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From page 45...
... A-·-~ -- . A -- Electrical Conductivity Total Akalinity Chemical Oxygen Demand Total Hardness Nitrates FIGURE 5-1 Well field areas supplying the Federal District where water quality testing indicates particular parameters are not in compliance with water quality standards.
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From page 46...
... WATER QUALITY IN THE DISTRIBUTION SYSTEM The Federal District's Central Control Laboratory at Xotepingo analyzes the water quality within the distribution system by sampling at certain hydraulic installations (entrance points for water delivered to the distribution system, pumping stations, and system storage tanks)
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From page 47...
... Results are averages for 1991 as reported by the Federal District Central Control Laboratory at Xotepingo. Federal District Counties Alvaro Obregon Atzcapotzalco Benito Juarez Coyoacan Cuajimalpa Cuauhtemoc Gustivo Madero Iztacilco Iztapalapa Magdalena Contreras Miguel Hidalgo Milpa Alta Tlahuac Tlalpan Venustiano Carranza Xochimilco Source: AIC-ANIAC, 1995.
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From page 48...
... Protection of public health is managed through crop restrictions rather than wastewater treatment. In 1991, the Urban Development and Ecology Ministry (SEDUE)
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From page 49...
... It is the third leading cause of infant mortality in the State of Mexico and fourth in the Federal District (mortality rates are 450 and 156.7 per 100,000 respectively; INEGI, 1991a)
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From page 51...
... . While much waterborne disease is associated with contaminated water sources and inadequate water treatment, protection of water quality during its distribution to the customer is of equal importance.
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From page 52...
... Chemicals of concern are nitrates, toxic metals and other inorganic pollutants, assorted volatile and semi-volatile organic solvents, agricultural pesticides, herbicides, and radio-chemicals. Toxic leachate from improperly disposed chemical wastes, leaky underground storage of industrial and energy-generating products, rainwater contaminated by air pollution, agricultural runoff, and mining wastes, are all potential contributors.
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Key Terms

  • federal district
  • drinking water
  • water supply
  • mexico city
  • central control

  • control laboratory
  • mortality rates
  • american health
  • ground water
  • pan american

  • oxygen demand
  • storage tanks
  • household tap
  • water sources
  • quality standards

  • tap water
  • water samples
  • city metropolitan
  • water contamination
  • infant mortality

  • surface water
  • quality water
  • organic nitrogen
  • main aquifer
  • household taps

  • chemical oxygen
  • contaminated water
  • chlorine residual
  • supply aquifer
  • household water


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