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<br />MUNICIPAL AND INDUSTRIAL WATER REQUIREMENTS
<br />AN'D PROBLEMS
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<br />by
<br />LEON W. JACKSON
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<br />Engineer, Headman, Ferguson and Carollo,
<br />Consulting Engineers, Phoenix, Arizona
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<br />INTRODUCTION
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<br />Among the many needs of a modern municipality,
<br />one of the most vital is an adequate, safe, and de~
<br />pendable supply of domestic water.
<br />The purpose of this paper is to present information
<br />which will lead to a better understanding of the water
<br />requirements and problems of municipalities and their
<br />relationship to those of the agficultural field. It is
<br />only through mutual understanding of all problems
<br />involved that we can correctly solve the many probM
<br />lems so closely inter-related.
<br />The scope of this paper is limited to the existing
<br />trends and normal pattern of growth and expansion of
<br />cities in arid regions where the Sources of raw water
<br />for domestic purposes are adequate, though not un-
<br />limited, for normal domestic and industrial activities.
<br />It is recognized that deficiencies in sources of water
<br />supply can and would seriously alter and over-ride
<br />the trends, factors, and influences which are later
<br />presented in this paper as being characteristic of
<br />specific cities.
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<br />WATER REQUIREMENTS PER CAPITA
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<br />The average per capita water requirement is a fac~
<br />tor obtained by dividing the total quantity of water
<br />required by the total number of people served with
<br />domestic water. This factor reflects many things
<br />about the life and habits of the people in a given
<br />city. It is the weighted average of many influences
<br />expressed as one factor to be used in the study of
<br />the past, present, and probable future requirements
<br />of municipal water.
<br />Temperature, rainfall, and humidity of an area rank
<br />. high in the order of importance in influencing the per
<br />capita water requirements. The mode of living, as
<br />reflected in the types and number of units of water
<br />using equipment, such as sanitary facilities, air con~
<br />ditioning equipment, washing machines, and cleaning
<br />equipment has its influence. The quantity of flower~,
<br />shrubs, and lawns and the number and types of in~
<br />dustries, institutions, or establishments such as
<br />hospitals and parks, also influence the average per
<br />capita water requirement.
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<br />The water fate structure has a very direct influ-
<br />ence upon the per capita use, and consequently it
<br />can be and often is used to artificially control the
<br />demand for water. This method, as well as the en~
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<br />forcement of laws and regulations on use of water, is
<br />sometimes used to curtail the use of water when the
<br />supply is insufficient to meet the demand or to pre~
<br />vent excessive or wasteful use of water.
<br />The general trend dudng the past twenty years,' as
<br />shown in Plate No.1, is toward an increased per
<br />capita use of water. This is a result of progressive
<br />changes in the influences previously referred to in
<br />this paper. Most of these normal changes have been
<br />such as to result in increased use of water.
<br />The average annual rate of increase in per capita
<br />use for cities in arid regions is about 4 gallons per
<br />capita per day per year.
<br />In some cases this trend toward increased use per
<br />capita levels off naturally as people get sufficient
<br />water for their needs. In other cases where an ab-
<br />normal or undue quantity of water is being used or
<br />where the supply is limited, due to limited sowce
<br />or limited facilities, the practice in many cities is
<br />toward some artificial control on the quantity of water
<br />used. It is not likely m feasible that the present
<br />upward trend in per capita use will continue for long
<br />at the existing rate of rise.
<br />By reference to Plate No.1 it can be seen that
<br />the average per capita requirements of water for nine
<br />different cities in Texas, New Mexico, Arizona, and
<br />Utah, all in relatively arid areas, range from 100
<br />gallons per capita per day for Santa Fe, New Mexico,
<br />to 260 gallons per capita per day for Yuma, Arizona.
<br />EI Paso, Texas, requires 144 gallons per capita per
<br />day, and Albuquerque, New Mexico, requires 152
<br />gallons per capita per day. The extremely high per
<br />capita quantity for :Vuma, Arizona, is influenced
<br />largely by the high temperatures and by very low
<br />water rates. The Salt Lake City high rate of 235
<br />gallons per capita per day reflects the relatively low
<br />water rates, as well as the water-using habits re...
<br />suiting fwm a long histmy of a plentiful supply of
<br />good, easily available water.
<br />Santa Fe, New Mexico, has a relatively low rate
<br />of per capita usage of 100 gallons per ,capita per day
<br />and, among other influences,arethe higher elevation,
<br />lower temperature, less irrigation and air condi-
<br />tioning requited, higher water rates and only a .small
<br />amount of light industry.
<br />El Paso, Texas, and Albuquerque, New Mexico,
<br />are similar in character and have similar per capita
<br />rates of about 150 gallons per capita per day, which
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