Longmont WC Plan 2008

• Project Type: Water Conservation Plan
• Contract/PO #: OE PDA 08-15
• Applicant: City of Longmont
• Project Name: City of Longmont Water Conservation Plan
• Title: City of Longmont Water Conservation Master Plan
• Date: 11/24/2008
• County: Boulder
• Water Conservation - Doc Type: Complete Plan

WATER CONSERVATION PLAN 2008
TABLE 7
Annual Water Loss Estimate (2007)1
Parameter
(1,000 gallons)
Comments
Treated Water Production
519091126
Water production leaving the water
treatment plants
Billed Authorized Use
510261985
Residential, commercial, irrigation
estimated hydrant meters
Unbilled Authorized Use
4051982
Unbilled metered, estimated
unbilled unmetered, City
Water Loss
4761159
Water Loss = Treated Water
Production — Billed Authorized Use
— Unbilled Authorized Use
%Treated Water Loss
8.1
% Water Loss = Water
Loss /Treated Water Production
1 Water loss estimate provided by City based on refined data gathering for meters
and authorized uses.
Residential accounts were not fully metered until the end of 2006 such that
estimating water loss for years prior to this is not as reliable. Water loss parameters
for 2007 are summarized in Table 7 below.
For 2007, the estimated water loss from the City's potable water system was 8.1
percent. Note that there are some known authorized uses that are not accounted for
in this analysis such as plant water use at Nelson - Flanders WTP. There are no clear
standards for an acceptable amount of water loss in a system, but historically 10 to
15 percent water loss has been considered acceptable. For comparison, a report
released in 2007 by Western Resource Advocates, titled Front Range Water Meter,
reported a range of water loss values from 2 percent to 17 percent based on thirteen
area communities.
The IWA /AWWA Water Balance method also has a formula to estimate the
theoretical low limit of leakage that could potentially be obtained if all available best
technologies were successfully applied. The theoretical estimate is based on the
miles of water mains, number of service connections, average pressure in the
system, and the distance of private water lines (to the curbstop) . Based on rough
assumptions for the distance of private water lines and an average system pressure
of 70 pounds per square inch (psi) the theoretical low limit of annual water loss for
the City would be 170,880 thousands of gallons, approximately 691,598 thousands of
gallons less than the City's water loss estimate for 2007. Comparing this theoretical
number to the estimate for 2007 is equivalent to a water loss of 1.8 percent. This "low
limit" number does not represent a realistic goal, but gives a theoretical reference
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