Rivanna Water and Sewer Authority
Water Demand Analysis
Technical Memorandum 1
Water Demand Forecasting Methodology
TO: Tamara Ambler, Rivanna Water and Sewer Authority PAGES: 19
SUBJECT: Regional Water Plan Water Demand Analysis Methodology Memorandum
FROM: Troy Kincer, PE
BY: Kim Shorter, PE
DATE: May 23, 2011
Background
The Rivanna Water & Sewer Authority (RWSA) is a wholesale water provider that produces and
distributes potable water to two customers; the City of Charlottesville (Charlottesville Public Utilities
Division) and the Albemarle County Service Authority (ACSA). These two customers receiving wholesale
water then directly retail the water to residential and commercial water customers. The City of
Charlottesville provides water service to the City of Charlottesville and the Grounds of the University of
Virginia (UVA). The ACSA provides water service to the urban areas in Albemarle County surrounding
the City of Charlottesville, as well as Crozet, the Town of Scottsville, and the Village of Rivanna. ACSA
also serves a research park and some other off-Grounds facilities owned by UVA or its foundations.
Figure 1 shows the location of the service areas within Albemarle County.
In addition to the RWSA, there are a number of smaller Community Water Systems (CWS) in Albemarle
County that produce and distribute drinking water. In 2009, there were 17 CWS including; Bedford Hills,
Burton Court Apartments, Earlysville Forest, Faith Mission Home, Forest Lodge Water Company,
Glenaire Subdivision, Innisfree Village, Ivy Farms Water Company, Keswick Estates, Langford Subdivision,
Little Keswick School, Miller School, Oak Hill Trailer Park, Peacock Hill Subdivision, Corville Farm
Subdivision, Woods Edge Subdivision, and Red Hill. Also within Albemarle County, there is a segment of
the population that is considered “self-served” which means they have a private well to supply their
individual home.
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Figure 1. Location Map of RWSA service area
CWS #1
4 2 0 4 Miles
CWS #2
#5 RESERVOIR
CWS #3
#2 WTP
CWS #5
#4 RESERVOIR
Crozet #6 RESERVOIR
CWS #15 #4 WTP
#3 RESERVOIR
CWS #6
CWS #16 UVA
CWS #7
#1 WTP CWS #8
Charlottesville
64
64 CWS #11 CWS #14
#3 WTP
CWS #10 #2 RESERVOIR
CWS #13
CWS #4
CWS #9 CWS #12
Village of Rivanna
COMMUNITY WATER SYSTEMS
Scottsville #1 CWS = FAITH MISSION
#2 CWS = INNISFREE VILLAGE
WATER TREATMENT PLANTS
#3 CWS = EARLYSVILLE FOREST
#1 WTP = CROZET WTP
#4 CWS = OAK HILL
#2 WTP = NORTH RIVANNA WTP #5 WTP
#1 RESERVOIR #5 CWS = BEDFORD HILLS
#3 WTP = OBSERVATORY WTP
#6 CWS = BURTON COURT
#4 WTP = SOUTH RIVANNA WTP
#7 CWS = CORVILLE FARM
#5 WTP = SCOTTSVILLE WTP
#8 CWS = LANGFORD
Legend SURFACE WATER RESERVOIRS #9 CWS = FOREST LODGE
Community Water Systems
#1 RESERVOIR = TOITER CREEK RESERVOIR #10 CWS = MILLER SCHOOL
RWSA Water Treatment Plants
Interstates #2 RESERVOIR = RAGGED MOUNTAIN RESERVOIR #11 CWS = PEACOCK HILL
Primary Roads #3 RESERVOIR = BEAVER CREEK RESERVOIR #12 CWS = WOODSEDGE
RWSA Surface Water Reservoirs
#4 RESERVOIR = SUGAR HOLLOW RESERVOIR #13 CWS = KESWICK ESTATES
Crozet
Scottsville #5 RESERVOIR = NORTH FORK RIVANNA RIVER #14 CWS = LITTLE KESWICK SCHOOL
UVA SURFACE WATER INTAKE
#15 CWS = IVY FARMS
City of Charlottesville #6 RESERVOIR = SOUTH FORK RIVANNA RIVER RESERVOIR
Village of Rivanna #16 CWS = GLENAIRE
Albemarle County
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RWSA is developing a Regional Water Supply Plan in accordance with the Virginia Local and Regional
Water Supply Planning Regulations (9 VAC 25-780) for all of the water users in the RWSA service area
which is defined as the “planning area” in 9 VAC 25-780. By regulation, the Regional Water Supply Plan
shall contain the following elements:
Description of existing water sources (9 VAC 25-780-70)
Description of existing water use (9 VAC 25-780-80)
Description of existing water resource conditions (9 VAC 25-780-90)
Assessment of projected water demand (9 VAC 25-780-100)
Description of water management actions (9 VAC 25-780-110 & 120)
Statement of need (9 VAC 25-780-130)
Maps identifying important elements (e.g., environmental resources, existing water sources,
existing significant water uses, proposed new sources, etc.) of the Water Supply Program
Copies of local ordinances or amendments that incorporate elements of the Water Supply
Program
Copies of resolutions from the local governments in the planning area approving the Water
Supply Plan
Records of local public hearing
One of the critical elements in creating the Water Supply Plan is to complete a Water Demand Analysis
that identifies the future demand for drinking water. RWSA retained AECOM to complete the water
demand analysis and develop the forecasts that will be used as the foundation for the Regional Water
Supply Plan. The Regional Water Supply Plan must be submitted by November 2, 2011 for review by the
Department of Environmental Quality and for approval by the State Water Control Board.
The Regional Water Supply Plan must be reviewed every 5 years. If circumstances upon which the plan
was based change, or new information indicates that water demands cannot be met by the alternatives
contained in the Water Supply Plan, then the Plan must be updated and re-submitted to the Virginia
Department of Environmental Quality for approval. Even if no changes have occurred that would
change the conclusions of the Water Supply Plan, it must be updated and submitted to the Department
of Environmental Quality for approval every 10 years.
The Local and Regional Water Supply Planning regulation contains specific requirements for the water
demand analysis (9 VAC 25-780-100). These requirements, in summary, include:
- Use of appropriate data sources and documented methodology
- Forecast demands for a minimum of 30 years and a maximum of 50 years
- Estimate the water demands for each decade (2010, 2020, 2030, etc.)
- Include projections for community water systems
- Include self-supplied water demands (private non-farm wells)
- Include self-supplied agricultural demand
- Consider the reduction in future water demands associated with water conservation and leak
detection programs
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The major tasks associated with this project include:
- Forecasting the water demands for a 50-year planning horizon in 10-year increments.
- Soliciting input on water usage from the various stakeholder groups and the general public.
- Communicating the water demand forecast methodology and water demand forecast results to
the stakeholder groups and the general public.
Stakeholders, advocacy groups, and citizen involvement will play a major role throughout the planning
process with RWSA. Stakeholders include elected officials, planning staff, community water systems in
the region, and representatives from the University of Virginia. AECOM will engage these groups and
the RWSA at important stages in the forecasting process to allow for relevant and available data to be
obtained and considered during the development of the water demand forecasts in the Regional Water
Supply Plan. Key milestones of the project are shown in Figure 2.
Presentations
Methodology
Draft Water Demands to Elected
Stakeholder Workshop Final Water
Worshop and "Office Boards and
Meetings and "Office Demands Report
Hours" Councils
(May 2011) Hours" (September 2011)
(July 2011) (September
(May 2011)
2011)
Figure 2. Key Water Demand Forecast Milestones
Public interest in water supply planning is high in the City of Charlottesville and Albemarle County
planning area. Much public dialogue has focused on the roles played by adverse economic conditions,
short-term drought management responses, and long-term water conservation efforts in recent water
use figures. This study will evaluate these and other issues affecting local water use to determine
whether potential trends may be identified and to ascertain the long-term impacts of any such trends on
future water demands.
For the RWSA, it is important to seek and obtain information and input from the water users and
providers in the planning area. RWSA intends to share information with these water users and providers
on the projected water supply needs, in order for the region to update its water supply planning using
specific methods required by state regulations. Obtaining, evaluating and considering relevant
information regarding water use and projected growth in the planning area is important to developing a
reliable water demand forecast.
The water demand forecasts will be developed based on the characteristics of four distinct character
areas within the regional water supply planning area; Urban, Rural, Town of Scottsville, and CWS areas.
These areas are defined below.
- Urban – City of Charlottesville, University of Virginia, urban portions of the ACSA
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- Rural – ACSA rural areas, including Crozet
- Town of Scottsville – area served by ACSA within the town limits
- Community Water Systems (CWS) – 16 independently-operated water systems, plus Red Hill
(operated by ACSA) and includes the self-supplied population
Introduction
The purpose of this memorandum is to provide an overview of the water demand forecast methodology
proposed by AECOM to estimate the future water needs for the Regional Water Supply Plan Planning
Area. This memorandum outlines the proposed methodology and also highlights the key decision points
that will be discussed at the methodology workshop. Gaining consensus on the methodology early in
the project will help maintain progress towards the November 2011 regulatory deadline for the larger
Regional Water Supply Plan.
The recommended methodology for calculating future water demands in simplistic terms is shown in
Figure 3. This method is based on the “Disaggregate Water Use Model” outlined in the American Water
Works Association (AWWA) M50 Water Resources Planning Manual (AWWA M50 Manual). The
Disaggregate Water Use Model forecasts future water use for each customer type by applying water use
patterns to the future customers within that specific water use category (e.g., single-family residential).
One example of the disaggregate water use model is shown in Figure 3. The residential water demand is
calculated by multiplying the number of people for each time period by the baseline per capita water
use. The employment water demand is similarly calculated by multiplying the future employment for
each time period by the daily per employee water use. This example adds non-revenue water, which is
discussed in greater detail later in this memorandum, as a percent of total water demand.
Figure 3: Summary of Water Demand Calculation
In reality, calculating water demand forecasts is not as simple as presented in Figure 3 and requires a
number of steps to interpret the data used to derive the forecasts. Figure 4 presents a more detailed
forecasting overview, adapted from AWWA M50 Manual, with the steps that will be used for this
Regional Water Demand Forecast. Due to the complexity of each step and the uncertainty associated
with future conditions, the final forecasts will be presented as a range of demands as indicated in Figure
4. The demands will be reviewed every 5 years as required by the Local and Regional Water Supply
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Planning regulation; therefore the expectation is that this range will be refined based on changed
conditions.
Figure 4: Process for Developing Water Demand Forecasts
This document is organized in the following sections:
- Historical Water Use Data – presents the sources of historical water use data and the
disaggregation of that data into customer categories, which includes non-revenue water.
- Normalized Water Use – presents a summary of the analysis for climate data and economic data
that will be used to evaluate whether the historical water use data is representative.
- Population and Employment Data –summarizes the available population and employment
forecasts.
- Baseline Water Demands – presents the methodology for developing the per capita and per
employee water use and the baseline future water demands.
- Water Demand Forecasts – presents an overview of the approach to forecasting future water
demands as well as estimating the demand reduction associated with future water conservation
efforts.
- Next Steps – presents a summary of the next steps to completing the future water demand
forecasts.
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Historical Water Use Data
Historical water use data (i.e., billing and production data) was provided by RWSA for the planning area
(City of Charlottesville and ACSA service area). The RWSA historical urban water production record was
provided for 1983 to 2010, as shown in Figure 5. The historical water use by customer category was
available from 2006 to 2010 for the City of Charlottesville and from 2004 to 2010 for the ACSA service
area. Additional historical water use for the urban area was available from 1983 to 2010; however the
early data is not available by customer category. The RWSA also compiled and provided water use data
for the CWS providers from 2008 to 2009.
As the data from 2006 to 2010 is more recent and is disaggregated into customer categories, this initial
step of the analysis will focus on the water use data for this period. This 5-year period included an
increase in unemployment and several unusual weather patterns (high and low rainfall); therefore,
earlier historical water production and billing data will be used as part of the normalization process.
Normalization is outlined in greater detail in the next step of the analysis, as shown in Figure 4. While
forecasting future water use based on current water use patterns is appropriate, there is a great degree
of uncertainty associated with these forecasts. These concerns are greater when a shorter record of
water use (5 years) is used to develop forecasts for a 50-year period. Therefore, a range of future
demands will be presented that represent the most likely future conditions in terms of water use to
account for any uncertainty.
Figure 5: Historical RWSA Urban Water Production Data (MGD)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
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Customer Categories
The disaggregate water use model involves analyzing historical water use to identify patterns specific to
each customer category. The historical water use data provided by the City of Charlottesville from 2006
to 2010 and ACSA from 2004 to 2010 is disaggregated into a number of customer types that allowed this
forecasting method to be used. To be consistent with the population and employment data (presented
later in this document), the customer categories will be grouped into three categories; residential,
employment, and irrigation categories. Table 1 presents the current billing categories for the City of
Charlottesville and ACSA and their relationship to residential, employment, and irrigation water use
categories.
Table 1. Overview of Customer Billing Categories
Entity Residential Employment Irrigation
City of Residential (single- Commercial Irrigation
Charlottesville family) Industrial
Multi-family Government (includes UVA)
Medical
ACSA Single-family Commercial (offices) Irrigation
Multi-family Commercial (other) Industrial
Institutional
DECISION POINT: Confirm that the existing billing categories are in the appropriate residential,
employment, and irrigation customer category.
Future water demand forecasts for the University of Virginia will be developed separate from City and
County projections, and will be disaggregated into the following categories: student/faculty housing,
academic facilities operations, and hospital and medical facilities operations to the extent that details
are available.
The data provided by the CWS were not divided into customer categories and some of the CWS did not
provide any water use data. The self-supplied customers (i.e., private wells) are not tracked specifically
but tend to be single-family dwellings. The number of self-supplied customers will be estimated based
on the total population and the population served by the water providers.
It is common to use the per capita method (from AWWA M50) for the CWS and self-supplied customers.
This method applies one water use rate to all customers in the service area, regardless of customer
category. In 2009, the CWS that reported water use consumed a total of 0.1 MGD of water compared to
the RWSA production of 9.34 MGD. Since the comparative water use is low, the per capita method is
recommended for the CWS and self-supplied customers.
DECISION POINT: Confirm that using the per capita model and a representative per capita for CWS and
self-supplied customers is appropriate.
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Estimating Non-Revenue Water
Non-revenue water, as defined by the AWWA, includes unbilled authorized consumption (i.e., fire
fighting, line flushing, etc.), apparent losses (i.e., water not billed through clerical error), and real losses
(i.e., leaks, main breaks) as shown in Figure 6. NRW will be calculated by subtracting the water billed to
customers by the City of Charlottesville and ACSA from the water produced by RWSA. Since NRW
includes unbilled authorized consumption and real losses (AWWA methods confirm that all water
systems will have an unavoidable level of leakage), it is rare to see a system with less than 10% NRW.
NRW above 20% is typically considered high and programs would be needed to target the highest areas
of NRW.
Figure 6. International Water Standard Water Balance (adapted from AWWA M50)
Any additional planned reduction in NRW based on this analysis would be considered as an existing or
new water conservation measure as discussed later in this methodology. Consideration will be given to
the impacts on NRW resulting from planned preventative flushing programs in the City of Charlottesville
and ACSA in the next 2 years as part of overall operational changes in the water system planned for
2014. RWSA plans to use chloramines for disinfection instead of free chlorine, to comply with national
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safety standards. If the existing NRW is very low, implementing a more robust line flushing program
may result in a net increase in the NRW.
Normalized Water Use
Weather and economic conditions can have a dramatic effect on water use patterns. For example,
during periods with higher than normal rainfall, water use temporarily declines, as water is not needed
for outdoor irrigation. During times of extremely low rainfall, mandatory and voluntary drought
restrictions reduce the normal water consumption. The economic conditions can also impact water use
as customers watch their monthly utility bills more closely and reduce discretionary water use (i.e.,
irrigation).
This section outlines the analysis that will be performed to determine if adjustments to the historical
water use data will be needed to represent “normal” conditions or if historical data is an appropriate
indicator of future water use. Normalization is an important step in the analysis, as using a lower than
normal baseline water use could result in insufficient water to meet the regional water supply planning
area needs.
Climate Data
Historical rainfall patterns were reviewed to identify years with irregular weather patterns. During
“wet” years, outdoor watering levels decline and during “dry” years there are often watering restrictions
that reduce typical consumption levels. Historical rainfall data, shown in Figure 7, is from the National
Weather Service rain gage located on the UVA campus near the McCormick Observatory. The gage has
a period of record from 1893 to the present.
For several years within the record, including from 1893 to 1922, only partial rainfall data was available
(i.e., only 11 months of data). However, a complete record of rainfall data was needed to determine if
the weather patterns from 2006 to 2010 are “normal”1. Where there was one month of missing rainfall
data, that month was replaced with data from the Free Union rain gage for 1955 to 2010 and from the
rain gage near the Observatory WTP for 1931 to 1954.
The average rainfall for Albemarle County was calculated to be approximately 47-inches per year based
on the years with complete rainfall data2. Years with rainfall below the average (green line in Figure 7)
are considered to be “dry” years and above this level are “wet” years. For the period of record, 2003
had the highest rainfall of record for this gage station at more than 74-inches. There was also a
pronounced drop in rainfall in 2007 with a gradual return to normal weather patterns by 2009 and
another drop in rainfall in 2010. Water use restrictions were in place in 2002 and 2007, the two years
with the lowest recorded rainfall in the last 20 years.
1
Normal in this context means void of extremes.
2
Calculated average based on the historical period at the National Weather Service rain gage on the UVA campus
for months with complete rainfall data.
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Figure 7. Historical Rainfall Data for Charlottesville, VA
80.00
70.00
60.00
Annual Rainfall (inches)
50.00
40.00
30.00
20.00
10.00
0.00
1920
1925
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year
A more detailed assessment of the rainfall patterns and the impacts of emergency drought actions on
water use patterns will be completed and presented for discussion at the draft water demand forecast
workshop.
Economic Trends
The U.S. Bureau of Labor Statistics provides trend data for the Charlottesville Metropolitan Statistical
Area3, including the unemployment rate and other economic indicators. The number of unemployed
persons from 2001 to 2010 presented in Figure 8 shows a steady rise in unemployment from 2007 to
2010. The highest period of unemployment was January 2010 and the lowest period was January 2001.
While the Charlottesville Metropolitan Statistical Area (MSA) unemployment remains much lower than
the national average, the change is significant and may be impacting current water use.
3
http://www.bls.gov/ro3/charlottesville.pdf
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Figure 8. Historical Unemployment Data for the Charlottesville MSA
7000
6000
5000
4000
Persons
3000
2000
1000
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
A more detailed assessment of the rainfall patterns and the impacts of the economy on water use
patterns will be completed and presented for discussion at the draft water demand forecast workshop.
Comparing more recent water use data to the historic water use data may help better understand the
impacts of rainfall and economy on water use.
Population and Employment Data
Population and employment data is available from a number of different existing sources: US Census,
Virginia Employment Commission (VEC), Weldon Cooper, Rivanna Water & Sewer Authority’s
Comprehensive Sanitary Sewer Interceptor Study, local comprehensive plans, Demand Analysis for the
Urban Service Area by Gannett Fleming, Places29 Master Plan, the Thomas Jefferson Planning District
Commission, and the Virginia Economic Development Profiles. Historical population data from the US
Census is shown in Figure 9 from 1960 to 2010. Historical employment data from the US Department of
Labor Quarterly Census of Employment and Wages (QCEW) is presented from 2001 to 2010 in Figure 10.
This historical population and growth patterns shows steady growth in the region while the employment
shows a decline, which is consistent with the unemployment presented in Figure 8.
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Figure 9. Historical Population Data (1960 – 2010)
160,000
140,000
120,000
100,000
80,000
60,000
40,000
20,000
0
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
TOTAL Albemarle County Charlottesville City
Figure 10. Historical Employment Data (2001 – 2010)
100,000
90,000
80,000
70,000
60,000
Employees
50,000
40,000
30,000
20,000
10,000
0
2000 2002 2004 2006 2008 2010
Charlottesville Albemarle Total
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The US Census data, shown in Figure 9, includes the entire population in Albemarle County and not just
the population served by public water supply. As this study is looking at the population served by RWSA
(through the City of Charlottesville or ACSA) or a CWS, it was considered more appropriate to use the
population forecasts developed by Albemarle County and the City of Charlottesville for the 2008 RWSA
Comprehensive Sanitary Sewer Study. The sewer study forecasted population for the City of
Charlottesville, ACSA urban area, and Crozet. The population forecasts for Scottsville4 and the CWS5
were added to develop the total population forecasts. The population forecasts for the water demand
study area are presented in Figure 11. The overall population will be divided into the four character
areas; urban, rural, Scottsville, and CWS. The urban area will be further subdivided into the City of
Charlottesville, ACSA, and UVA based on available data.
Figure 11. Population Forecasts (2010 – 2060)
200,000
180,000
160,000
Population (persons)
140,000
120,000
100,000
80,000
60,000
40,000
20,000
0
2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060
Year
RWSA Sewer Study Total Water Demand Study Area
The RWSA sewer study did not include separate employment forecasts. Employment forecasts are
available through the Virginia Employment Commission for the Piedmont Workforce Network which is a
greater area than this water supply study. Therefore, future employment will be estimated based on a
ratio of population to employment and/or households to employment based on guidance from the
water purveyors. The ratio will be distinct for each of the four character areas; urban, rural, Scottsville,
and CWS.
4
Scottsville population was estimated based on discussion with staff and historical trends.
5
Population served by the CWS were considered remain consistent throughout the planning horizon as the wells
were designed based on existing use.
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DECISION POINT: Confirm that the methodology for forecasting population and employment numbers
are appropriate.
Baseline Water Demands
The baseline water demands represent the future water need if the existing trends remain constant into
the future. The projected baseline demand will be calculated by multiplying the population from the
previous section by the residential per capita water use and the employment by per employee water
use, as shown in Figure 3. The water demands will be developed for each of the four character areas;
urban, rural, Scottsville, and CWS. The urban baseline water demand will be further disaggregated into
the City of Charlottesville, ACSA urban, and UVA.
There are several types of per capita use that will be discussed in this methodology, as shown in Table 2.
The residential per capita and per employee use do not account for NRW and therefore must be
multiplied by the NRW percent factor.
Table 2. Per Capita Definitions
Term Definition
Overall per capita Reflects the total water produced by RWSA divided by the total
population; includes NRW and employment in one indicator.
Residential per capita Reflects the total water use by single-family and multi-family accounts
divided by the population.
Per employee Reflects the total water use by commercial, industrial, and institutional
accounts divided by the number of employees.
The historical per capita water use will be developed for each of the customer categories shown in Table
1 based on the consumption data provided by RWSA.
The per capita water use will be calculated based on the following steps:
1. The number of persons served by the City of Charlottesville and ACSA will be calculated by
multiplying the total number of residential accounts by 2.35, the average number of people per
household for the City of Charlottesville based on the U.S. Census American Community Survey6
as a five-year average from 2006 to 2009.
2. The per capita water use will be calculated by dividing the water billed to residential customers
by the population served as identified in Step 1.
6
http://factfinder.census.gov/servlet/ACSSAFFFacts?_event=ChangeGeoContext&geo_id=05000US51540&_geoCo
ntext=&_street=&_county=charlottesville&_cityTown=charlottesville&_state=04000US51&_zip=&_lang=en&_sse=
on&ActiveGeoDiv=&_useEV=&pctxt=fph&pgsl=010&_submenuId=factsheet_1&ds_name=ACS_2009_5YR_SAFF&_
ci_nbr=null&qr_name=null®=null%3Anull&_keyword=&_industry=
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The per employee water use will be calculated following a similar process looking at the current number
of employees and the employment water use for 2006 to 2010.
The individual overall per capita water use will be calculated for each CWS that provided data. An
average overall per capita for CWS will be developed then applied to the CWS and self-supplied
population (per capita method).
Water Demand Forecasts
The baseline water demands represent an extension of current trends and are a starting point for other
considerations. Starting from the baseline water demand forecasts, different scenarios will be
considered to determine the range of future water demands that are possible. These scenarios will be
reviewed at the draft water demand forecast workshop and then the most likely scenario, or
combination of scenarios, will influence the range of future water demands.
Some of the scenarios may include:
- Continued implementation of water conservation programs
- New water conservation programs
- Increased population and/or employment (i.e., increase in student enrollment at UVA or
increased development activity)
- Decreased population and/or employment (i.e., permanent protection of the Biscuit Run tract as
a State Park)
- Other changes in water use patterns
The draft water demands will present a range of future water use numbers that will take into account
blend of the various scenarios that could impact future water use. Stakeholder, advocacy group, and
citizen input will have an opportunity to influence these scenarios and will be valuable in building a
reliable range of future water demands.
Water Conservation Analysis
At least one of the future scenarios will address the ongoing implementation of the existing water
conservation programs. The City of Charlottesville and ACSA have implemented many water
conservation initiatives and have considered a number of additional water conservation measures in the
past (outlined in the Water Conservation Study Report, 2009). Table 3 summarizes the current and
planned water conservation initiatives for both the City and ACSA.
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Table 3. Current and Planned Water Conservation Programs
Program Initiatives City ACSA
Current Planned Current Planned
Water Conservation Posters inside City Buses
Low Flow Toilet Rebate Program
Public Awareness Campaign for Free Indoor
Conservation Kits
Water Conservation Webpage Expansion
Water-wise Landscaping Demonstration Garden
Water-wise Landscaping Literature Distribution to Plant
Nurseries
Online Residential Water Use Calculator
Rain Barrel Pilot Program and Program Expansion
Green Team Outreach
Carwash Certification
Education Presentation to Business Groups/Individual
Businesses
Education Presentation to Neighborhood Groups & MF
Housing
Regular Ad Campaign, Year Round
Drought Public Notification Plan
Multi-Family Homes Retrofitted w/ Low Flow Toilet &
Conservation Kit
System Leak Detection
Aging Infrastructure Replacement
Rainwater Harvesting System Installation on Multiple
City Properties
Conservation Leader Program
Business Outreach
Water Conservation Results Monitoring
Water Restrictions Rules & Regulation
Conservation Leader Program
Cost Efficiency Study
Water Reuse Project with UVA
Water Conservation Kit Distribution to MF Homes
City Water Reuse Guideline Development for
Homes/Businesses
System Development for Updating all City Departments
Low Flow Toilet Vouchers
Rainwater Harvesting System Installation on Additional
City Properties
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Program Initiatives City ACSA
Current Planned Current Planned
Conservation Study
Rainwater Harvesting System Installation on ACSA
Warehouse
Toilet Rebate Program Expansion
Conservation Kit Distribution
Rainwater Harvesting Expansion
Time of Day Watering Adoption
Rate Structure Evaluation Changes
DECISION POINT: Confirm that the representation of the existing and planned water conservation
programs is accurate.
Estimating the benefits of water conservation measures requires a great deal of professional judgment.
As a number of previously described factors influence water use patterns (climate, economy, etc.), it is
very difficult to extract the benefit associated with water conservation measures. Additionally, it is very
difficult to identify the potential for additional conservation savings. For example, it is relatively easy to
estimate the number of toilets in a community but not how many have already been replaced with a
low-flow fixture and how many of those without low-flow fixtures that would choose to participate in a
replacement program. Therefore, a range of water conservation potential will be developed and
presented for discussion at the draft water demand forecast workshop. The range of conservation
potential will include passive conservation associated with the natural replacement of older fixtures
with more efficient fixtures as well as the active water conservation programs outlined in Table 3.
It is also important to note that this analysis addresses water conservation measures and not emergency
drought response. Water conservation includes programmatic and long-term actions to reduce water
demands, whereas emergency drought response actions are temporary in nature. It is not appropriate
to plan for the future based on the water use during an emergency and therefore only long-term water
conservation actions will be considered in this analysis.
Several analyses will guide the range of water conservation potential for the water supply planning area.
These include:
- Comparing per capita water demands to national standards. If the water supply planning area
already has a very low per capita water demand, it is unlikely that significant additional savings
can be achieved as there are diminishing returns.
- Considering the percentage of water use that is indoor versus outdoor. While some savings can
be achieved through plumbing retrofits, these savings are typically smaller than the savings
available through reduction of outdoor water use. Typically, a range of 10 to 20 percent of the
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total residential water use is for outdoor irrigation. The outdoor water use will be estimated by
looking at the historical winter average water use, as typically there is little to no irrigation in the
winter months.
- Estimate the total water use by indoor end uses (i.e., toilets, clothes washers, etc.). The AWWA
Research Foundation (AWWARF) Study “Residential End Uses of Water” 7 presents the
percentage of overall single-family water use associated with each end use, as shown in Table 4.
The estimated percentage of water use by end use will be multiplied by the single-family water
use and then used to refine initial estimates of water conservation potential from certain
conservation programs. For example, the total conservation potential for a toilet rebate
program cannot exceed the total volume of water used for toilet flushing.
Table 4. Water Use Percent by End Use Category
End Use Category % of Total Indoor
Water Use
Toilets 27
Clothes Washer 22
Showers & Baths 18
Faucets 16
Leaks 14
Dishwasher & Other Domestic 3
Total 100
Based on these considerations, the benefit in terms of demand reduction associated with water
conservation will be estimated. The recommended water conservation savings and results will be
presented at the Draft Forecast Workshop.
DECISION POINT: Discuss the possible scenarios for future water demands that should be considered.
Next Steps
The draft water demand forecasts will be developed based on the input provided at the Methodology
Workshop as well as additional data received by the stakeholders. The draft water demand forecasts
will include the baseline demands as well as different scenarios which will be presented at the Draft
Forecast Workshop for discussion. Refinements to the draft forecasts will be made based on the input
received at the Draft Forecast Workshop before publishing the final water demand forecasts.
7
Residential End Uses of Water, Mayer, AWWARF, 1999.
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