C150069 Feasibility Study

• Contract/PO #: C150069
• Contractor Name: Colorado State University
• Contract Type: MOU
• Water District: 0
• Loan Projects - Doc Type: Feasibility Study

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Rcsidcntial Sccondary Water Mctcrs - Rescarch Proiect

In order to meet future needs brought about by growth, Utah must promote effective
water conservation and water management technologies. This, along with carefully
planned water developments, will secure sufficient water for the future.1

The Division of Water Resources has estimated that Utah's total per capita water use is 321
gpcd, with an estimated 143 gpcd being used outdoors2. The amount of water supplied for
outdoor use is significant in Utah. One way that Utah is taking part in water conservation is by
installing secondary water systems to relieve demand on drinking water supply. Of the
secondary water services that convey irrigation water, very few are metered. Metering
secondary water provides accountability for water use and encourages water conservation.

In a report written by the Colorado State University Water Lab in September 2003, the following
comment regarding culinary water metering was made:

In recent years, metering has increased dramatically. Although residential in-house water
demand has been generally found to be relatively inelastic (i.e., not very susceptible to
changes in use due to metering), outdoor use does change with metered pricing. Water use
for singlejamily dwellings with meters is often lower than water use for singlejamily
dwellings that are charged a flat rate, and much of this reduction is probably in outdoor
water use. In short, such factors as income and lot size held constant, outdoor water use
can be effectively curtailed through metering3.

As stated in the Utah State Water Plan, the Utah State Legislature made the following
recommendation to promote water conservation:

Provide incentives for more efficient water use by using a volume rate structure with
discounts for efficient use as well as penalty charges for water wasted. Such a rate
structure should be supported by trained staff and appropriate tools to assist water
wasters in reducing use.

According to water utility personnel and some meter vendors, meters that were designed for
clean, drinking water are not capable of performing efficiently under the harsh environment
that secondary water presents. Much of the irrigation water in the Salt Lake Valley, Utah comes
from Utah Lake, which contains higher than normal concentrations of sand, silt, and clay
particles, organic matter, salts, and other chemicals that can build up on and erode the inner
components of a standard drinking water meter. In the Weber Basin (north of Salt Lake City,
Utah), test meters on irrigation lines have been plagued with alkali build-up, causing them to
seize over time. At present, a reliable and economical meter for residential secondary water
systems has yet to be found.

From the Utah Water Plan:

Although secondary systems do free up treated water supplies for drinking water
purposes, it is important to recognize that they generally result in higher overall water
use than a typical potable (culinary) water system... consumers use more water outdoors
in [areas] where inexpensive un-metered secondary water is available than consumers in
other [areas]. One way to deal with this over-use is to meter the water and charge
according to an incentive pricing rate structure. Conventional meters plug up and wear
out quickly on secondary systems. Filtering the water to a level where conventional
meters will function properly or using a meter under development that ca~ function in
such condition should be considered.

The Utah Division of Water Resources has been actively involved in water conservation and
continues to look for ways to reduce secondary water used by consumers. Specific examples of

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