Alternative Water Supplies in Texas
Central Texas Water Conservation Symposium
Jorge A. Arroyo, PE
Water Management Consultant
February 2014
ALTERNATIVE…. TO WHAT?
…WHEN IS AN ALTERNATIVE NO
LONGER AN ALTERNATIVE?
NOT AN ALTERNATIVE TO WATER
CONSERVATION
Alternative Water Supplies
•
•
•
•
Rain collection systems
Water reuse
Managed aquifer recharge
Desalination
Rain Collection Systems
Source: Texas Water Development Board
Rain Collection Systems: Sole Source
•
•
•
•
•
Kight Residence RWH System- Boerne
Source: Texas Water Development Board
Volume of rain
Water use
Storage
Treatment
Operation and
maintenance
RWH System
Sizing Calculator
Change to fit your conditions
Catchment Area (sq. ft.)
Monthly Indoor Demand (gals)
Outdoor Demand (gals)
Water in Storage to Begin (gal)
Tank Size (gal)
2,500
3,000
150
0
10,000
http://www.twdb.texas.gov/innovativewater/rainwater/resources.asp
Indoor
demand
January
February
March
April
May
June
July
August
September
October
November
December
3,000
3,000
3,000
3,000
3,000
3,000
3,000
3,000
3,000
3,000
3,000
3,000
Irrigation
0.0
0.0
150.0
150.0
150.0
150.0
150.0
150.0
150.0
150.0
0.0
0.0
Total
demand
3,000
3,000
3,150
3,150
3,150
3,150
3,150
3,150
3,150
3,150
3,000
3,000
Average
rainfall
2.12
2.41
2.23
2.97
4.02
3.39
1.96
2.21
3.17
3.44
2.68
2.35
Collection
surface size
Gallons/ft2
collection
coefficient
2,500
2,500
2,500
2,500
2,500
2,500
2,500
2,500
2,500
2,500
2,500
2,500
(*) starting with water in storage
Rainwater Harvesting
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
0.62
Efficiency
factor
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
0.85
Rainfall
collected
(85%
efficiency)
2,792
3,179
2,941
3,907
5,294
4,460
2,578
2,907
4,175
4,528
3,536
3,099
End of
month
storage (*)
0
0
0
519
2,664
3,974
3,402
3,159
4,184
5,562
6,099
6,198
Rain Collection Systems – Institutional
Redbud Center - Lower
Colorado River Authority,
Austin
Source: Texas Water Development Board
Rain Collection Systems: Subdivision
• Subdivision-Scale Rainwater Harvesting
Systems as a Water Supply Strategy
– The Meadows Center for Water and the
Environment: Texas State University, San Marcos
– Feasibility, facility design and management
protocol, backup supply
– Texas Hill Country.
Indirect Water Reuse
Direct Water Reuse
2012 State Water Plan
Recommended Water Management Strategies
3,500,000
3,000,000
Acre-feet/yr
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
2010
New Major Reservoirs
Reuse
ASR
2020
2030
Conservation
Desalination
Other
2040
2050
2060
Other Surface Water
Conjunctive use
Groundwater
12
Reuse to be added in the next 17 years*
Region
* 2012 State
Water Plan-DB12
C
E
F
G
H
I
K
L
M
N
O
Total
2010 decade
1,937
18,723
168
54,311
21,666
3,537
250
100,592
2020 decade
229,825
4,312
12,380
21,610
33,813
2,872
8,765
4,380
7,474
2,240
327,671
13
Managed Aquifer Recharge
Aquifer Storage and Recovery
In operation
• Kerrville
• El Paso*
• San Antonio
Potential
• Eastern Kerr County
• New Braunfels
• Guadalupe Blanco River
Authority (Lulling)
• Barton Springs Edwards
Aquifer District
• Legislation filed to facilitate ASR projects
• 83rd Texas Legislature – HB 3013
Desalination of Ocean and Brackish
Groundwater Sources
 367 miles of coastline
 Availability of sites
 Proximity to demand
centers
 Texas has an estimated 2.7
billion acre-feet of brackish
groundwater
Concentrate and power
Saline Water
Desalinated Water
Brackish Groundwater Desalination
18
• 120 million gallons per
day
• 44 facilities [25,000 gpd
or more]
• El Paso’s Kay Bailey
Hutchison Brackish
Groundwater
Desalination: 27.5 MGD
Innovation in water supply
• Increase water supply efficiency
• Sustainable use of sources
• Cost of innovation
– Research
– Demonstration