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WHAT MAKES UP TUCSON’S WATER DISTRIBUTION
SYSTEM?
Sources of Water - Water pumped from an
aquifer to pipes for distribution and delivery has been the
source of much of Tucson’s water. Tucson’s newest available
source of water is the CAP, which brings water from the
Colorado River. Tucson also has a system for using treated
wastewater on facilities such as golf courses and parks.
Pipelines - Large pipelines (“water mains”)
bring water from its source to central points, and smaller
pipes distribute that water throughout the community.
Reservoirs - These are storage areas that
hold water until used. Reservoirs are important for balancing
supply and demand and for ensuring that an extra amount of
water is in reserve for fire fighting. At one time, elevated
storage tanks provided adequate supplies of water. With our
large population, however, huge reservoirs are needed, with
capacities ranging from one million to twenty million gallons
of water.
Booster Stations - Since Tucson is not flat
nor completely situated downhill from its water supply,
booster pumps are needed to boost the water to higher
elevations.
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Many pools are not built at the same time as the home, but rather
within the first seven to eight years after the home is constructed.
And once constructed, pools are rarely removed. Pool removal can
cost over $10,000 and usually reduces the value of the home. This
suggests that the best time to provide outdoor water conservation
messages to homeowners is soon after they’ve moved into a newly
constructed home and before they have made landscaping and pool
decisions.
One of the few ways to reduce pool water use is covering the pool
when it is not in use to minimize evaporation. A survey of newer
homes in Tucson revealed that approximately 60 percent of home pools
have pool covers. But pool covers are used only about half the year.
Usage is at a minimum during the summer swimming season to allow
convenient and frequent access to the pool. Also covers are not used
in the summer because they cause the water to become uncomfortably
warm. Peak cover usage surprisingly is not in winter, but in the
fall and spring, when pool users are trying to extend the swim
season. Lower pool cover usage in the winter may reflect a desire to
protect the cover from sun damage while evaporation rates are the
lowest.
Water for evaporative cooling systems accounts for around five
percent of outdoor water use in Tucson. (Evaporative cooling is
classified as an outdoor water use because it results in water being
consumptively used and not returned to the sewage system as is the
case with other indoor uses.) In 1992, approximately 79 percent of
homes in Tucson had evaporative coolers. At that time approximately
59 percent of households had only an evaporative cooler; 21 percent
had both a cooler and an air conditioner; and 19 percent had only an
air conditioner. As air conditioners have gained popularity in new
construction, the percentage of Tucson homes with evaporative
coolers, along with the amount of outdoor water devoted to
evaporative cooling, has declined. Approximately 85 percent of new
construction surveyed in 1996 had only an air conditioner, 11
percent had both an air conditioner and an evaporative cooler, and
four percent had only an evaporative cooler. |
HIGHER WATER USE TRENDS
While newer homes have more low-flow plumbing fixtures and appliances
and are likely to have less turf and no evaporative cooler, some trends in
new construction cancel out these conservation gains. For example, newer
homes are more likely to have water using amenities such as pools, spas
and whirlpool tubs. Further, new apartment complexes and condominiums are
more likely to have large amounts of turf and landscaping, as well as
pools.
The number of homes with outdoor misting systems grew through the early
and mid-1990s. These systems spray droplets of water into the air that
evaporate to cool an area. Although manufacturers of misting devices claim
water efficiency, few residential misting systems are as effective or
water-efficient as advertised, and some are poorly designed. System
emitters can scale up or corrode, producing drips instead of the intended
mists. A survey of Tucson Water customers in 1992 showed that three
percent had misting systems. A Metro Water survey conducted about 1995
indicated that seven percent of homes had misting systems, and a 1997
survey of new housing indicated that 12 percent of sampled homes had them.
The 1997 survey showed that those systems were used an average of 3.4
times per week, and that the main use was for cooling pets left
outdoors.
The trend in cooling system design is toward greater water use. The
latest models of evaporative coolers are designed to prolong the life of
the cooler by draining water after a certain number of hours of operation.
This prevents mineral content from building up and corroding metal cooler
parts and scaling up the pads. Some new coolers, however, empty the pan
automatically after only a few hours of operation. This is excessive
considering Tucson-area water quality. In older coolers, water collects in
the bottom of the cooler and can be drained using a bleed-off valve. Some
new air conditioners also use water. Manufacturers can achieve higher
efficiency ratings by dissipating heat generated by the unit in an
attached evaporative cooler.
Some water-using indoor appliances also are starting to use more water
in settings designed to handle heavy loads. For example, Consumer Reports
found that while new dishwashers have a greater number of settings to
better match water use with job size, the power-scrubbing option available
on many models means significantly higher water use. New dishwashers use
between four and 13 gallons per load on normal settings, but can use
significantly more when set for the dirtiest loads. In contrast, washing
dishes by hand uses three to five gallons per load.
WATER RATES AND CONSERVATION
For decades water has been priced as if it were free. What people pay
for is the cost of capturing the water, delivering it to them and making
sure it is safe to drink. People who pump their own water pay to build and
operate their wells, but they do not pay anyone for the water itself.
ADWR, however, does charge well owners a small pumping fee which goes
primarily toward conservation and augmentation (water banking) programs.
In some states people pay an annual fee for their pumping permit which
recognizes that the state owns the water and sets certain conditions for
people to use it.
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