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TEXT 6
WATER SUPPLY SOURCES
Water supplies may be obtained from surface or ground sources, by expansion of
existing systems, or by purchase from other systems. The selection of a source of

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supply will be based on water availability, adequacy, quality, cost of development and
operation and the expected life of the project to be served. In general, all alternative
sources of supply should be evaluated to the extent necessary to provide a valid
assessment of their value for a specific installation. Alternative sources of supply
include purchase of water as well as consideration of development or expansion of
independent ground and surface sources. A combination of surface and ground water,
while not generally employed, may be advantageous under some circumstances and
should receive consideration. Economic, as well as physical, factor must be
evaluated. The final selection of the water source will be determined by feasibility
studies, considering all engineering, economic, energy and environmental factors.
TEXT 7
GROUND WATER SUPPLIES
Ground water is subsurface water occupying the zone of saturation. A water bearing
geologic formation which is composed of permeable rock, gravel, sand, earth, etc.,
and yields water in sufficient quantity to be economical is called an aquifer.
Unconfined water is found in aquifers above the first impervious layer of soil or rock.
This zone is often referred to as the water table. Water infiltrates by downward
percolation through the air-filled pore spaces of the overlying soil material. The water
table is subjected to atmospheric and climatic conditions, falling during periods of
drought or rising in response to precipitation and infiltration. A confined aquifer is
defined as the aquifer underlying an impervious bed. Areas of infiltration and
recharge are often some distance away from the point of discharge. This water is
often referred to as being under artesian conditions. When a well is installed into an
artesian aquifer, the water in the well will rise in response to atmospheric pressure in
the well. The level to which water rises above the top of the aquifer represents the
confining pressure exerted on the aquifer. Materials with interconnecting pore spaces
such as unconsolidated formations of loose sand and gravel may yield large
quantities of water and, therefore, are the primary target for location of wells. Dense
rocks such as granite from poor aquifers and wells constructed in them do not yield
large quantities of water. However, wells placed in fractured rock formations may
yield sufficient water for many purposes.