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Water Demand Trends,Efficiency and the Future
of Urban Water Use
PETER MAYER, P.E.WATER DEMAND MANAGEMENT
Seattle Public Utilities - 1990
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Annu
al A
vera
ge M
GD
Actual Demand
Firm Yield
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1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070
Annu
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vera
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GD
Actual Demand
Current Firm Yield
Forecast WithoutConservation
2013 Forecast
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1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070
Annu
al A
vera
ge M
GD
Actual Demand
Current Firm Yield
Forecast WithConservation
Forecast WithoutConservation
New Supply
70+ Years
A brief history of demand forecasting in Seattle
Conservation Saved Seattle $725 million
PV Cost of New Supply $800 Million
PV Cost of Conservation: $ 75 Million_______________________________________________________________
NPV : $725 Million
Water Use in the US, 1900 - 2010
Includes fresh and saline water. Source USGS and Pacific Institute 2015
M&I Water Use in the US, 1900 - 2010
Source USGS and Pacific Institute 2015
Public Withdrawals in the US – 1950 - 2015
Source USGS, AWE, and WaterDM 2017
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1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
gallo
ns per cap
ita per day (g
pcd)
Public Sup
ply With
draw
als (billion
gallons per day)
US Public Supply Withdrawals and GPCD
Public Withdrawals gpcdSource: USGS Estimated use of water in the United States (2010, 2015).
Metropolitan Water District of Southern California 1985 - 2015
36% reduction in per capita use over 30 year period
New York, New York
Tucson Water - Annual Production (1940-2016)
CAP ProductionPotable Production TARP Production Reclaimed Production
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Wat
er P
rodu
ctio
n fo
r TW
Ser
vice
Are
a (A
cre-
Feet
)
1940 1950 1960 1970 1980 1990 2000 2010Year
2016 2016
CAP
Reclaimed Water
TARP
Total Potable Water Use at 1985 Level
Massachusetts Water Resources Authority
Residential End Uses of Water
Residential Indoor GPCD
1999 vs. 2016 = 15.4% reduction
2016 vs. HE = 37.4% reduction
Indoor GPCD
Indoor GPCD Comparison
Toilet Clotheswasher Shower Faucet Leak Other Bath Dishwasher
REU1999 18.5 15.0 11.6 10.9 9.5 1.6 1.2 1.0REU2016 14.2 9.6 11.1 11.1 7.9 2.5 1.5 0.7
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Gallons per cap
ita per day (g
pcd) Statistically
significant reductions in:• Clothes washer• Toilet• Dishwasher
Toilets
REU1999 REU2016
Number of houses logged 1,187 762
Average flushes/household per day 12.4 13
Average flushes per person per day 5.05 5.0
Average flush volume 3.65 ± 0.06 gal 2.6 ± 0.01 gal
Average per capita toilet use (gpcd) 18.5 14.3
22.7% reduction in avg. per capita toilet use.
Total Bath ClothesWasher
DishWasher Faucet Leaks Other Shower
Hot 45.5 2.6 4.4 2.2 15.4 2.1 0.9 17.8Cold 92 2 18 0 12 16 3 9
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160Av
erage Daily Hou
seho
ld Use (g
phd)
Hot and Cold Water Household Use
N = 94 homesAverage66.8% cold33.2% hot
Hot Water Per Capita Use
Efficiency Improvements
Water & Sewer Bill – 5, 25 kgal
Residential Outdoor Water Use
0%
5%
10%
15%
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25%
30%
10%
20%
30%
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60%
70%
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90%
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More
Relativ
e Freq
uency
Application Ratio
I‐‐‐Low/Deficit‐‐‐‐I‐‐‐‐On Target‐‐‐‐‐I‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐Excess‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐I
How much more efficiency? A lot. We’re …half way there! New technology Outdoor efficiency Leak detection Advanced metering Water loss control Customer engagement through
data and information Peak management
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Watering duration: 15 min
Waters on Mon, Wed, Fri
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Dan
Niko
Jill
Mark
PRESSURE ZONE
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Future Trends• Technological change• Behavioral change• More intense and frequent drought• Demand fluctuations• Water demand management at the retail level
