Estimated Water Use Report - Southwest Florida Water ...

2005 Estimated Water Use Report
comparable when a system supplies a large
amount of water to non-residential users, is
subjected to large unaccounted for water use
patterns (such as a major pipeline failure), or
has access to reuse.
Adjusted Gross Per Capita Water Use
When Unadjusted Gross Per Capita water use
is refined by subtracting “significant use”,
“environmental mitigation” water, it is termed
“Adjusted Gross Per Capita.” Significant use
refers to the sum of the average consumption
of all non-residential water customers who
each use at least 25,000 gpd or five percent of
system use, such as commercial users.
Environmental mitigation refers to the
pumping of water to replenish lakes and
wetlands, which have been impacted by
nearby Public Supply withdrawals, but only
when this replenishment is required as a
condition of a water use permit.
The refinement of per capita water use data
has a special purpose, particularly in the
District’s declared Water Use Caution Areas. In
these portions of the District, Public Supply
permittees are required to meet certain percapita-water-demand-reduction
goals.
Adjusted Gross per capita data allow for more
equitable permit-to-goal as well as permit-topermit
comparison because it compensates for
the effects of large non-residential users
whose consumption may benefit an area,
which extends far beyond a specific
permittee’s service territory. Also, when
communities fail to report a significant use
(such as a power plant) on the voluntary
survey, Table A-1 may show an unusually high
gross per capita figure. In Table A-1 Public
Supply Adjusted Gross Per Capita is examined
for only those permittees located within a
WUCA. During calendar year 2005, adjusted
gross per capita within the District averaged
approximately 111 gpcd (Table A-1).
Residential Per Capita Water Use
This measurement accounts for the portion of
publicly supplied water that is used for
residential purposes only. The percentage of
residential water use reported to the District
by a utility is multiplied by their total water use
Southwest Florida Water Management District
to quantify how much water is used for
residential purposes only. Residential Per
Capita differs from Unadjusted Gross Per
Capita and Adjusted Gross Per Capita because
it does not include any non-residential uses.
Due to the limitation in billing systems, not all
public supply systems are able to separate
residential from other types of water use.
Calculation of residential water was performed
in Table A-2. If a utility supplies a large
number of non-residential customers with
water, their residential per capita will be
significantly lower than their Unadjusted Gross
Per Capita. For example, in 2005, the 116
gpcd (Table A-1) unadjusted gross per capita
water use of the Manatee County Public
Utilities service area is brought down to a
residential per capita of 83 gpcd when nonresidential
customers are removed (Table A-2).
For those permittees able to provide sufficient
demand details, the average residential per
capita water use was estimated to be 80 gpcd
during calendar year 2005 (Table A-2). County
averages of residential per capita water use
are compared in Table 2.
Unaccounted for Water
Unaccounted for water (also referred to as
“UAW”) is the portion of water that enters the
distribution system and is “lost.” Several
situations can be contribute to UAW, including
transmission pipeline failures, valve box leaks,
unauthorized service connections, and
production meters that are over–registering.
Water used for customary purposes, such as
firefighting and line flushing that can be
estimated, is considered “accounted” and,
therefore does not need to be included in a
permittee’s UAW amount.
Although a high UAW value generally
indicates the need to address one or more of
the problems listed above, a low UAW value
does not necessarily indicate a tight, efficiently
run system. If the source (withdrawal) meters
are under-registering, a permittee may falsely
appear to have a low or possibly negative
UAW (i.e., the system bills for more water that
it supposedly produces). Production and
customer meter accuracy can only be ensured
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