Water is the lifeblood of our state, and a reliable water supply is vital to the Texas economy and its growing population. According to the 2022 State Water Plan from the Texas Water Development Board (TWDB), Texas’ water demands are projected to increase by approximately 9 percent over the next 50 years, while its existing water supplies are projected to decline by approximately 18 percent during that time. It is crucial for Texas to secure the water resources necessary to sustain its growth and provide for the future. One of the strategies Texas is using to increase its water supply is desalination.
What is Desalination?
Desalination refers to the removal of excess salt and other minerals from groundwater, surface water or reclaimed water sources to create fresh water – making otherwise unusable water suitable for human consumption, irrigation, industrial applications and other purposes. In Texas the process is used primarily in places where the groundwater or surface water is too salty or highly mineralized for most uses without treatment.
According to TWDB's The Future of Desalination in Texas(PDF), there are 406 municipal brackish groundwater desalination plants in the U.S. – 40 percent in Florida, 14 percent in California and 13 percent in Texas – most of which (72 percent) use reverse osmosis in the treatment process.
Process
The process used for desalination depends on factors such as the number of dissolved solids, temperature and other physical characteristics of the source water, but the two most common methods incorporate either thermal (i.e., distillation) or reverse osmosis technologies. In thermal desalination, saltwater is heated up, and the resulting water vapor is condensed and collected. In reverse osmosis desalination, saltwater is pushed through a series of filtering membranes at high pressure to remove salt, certain minerals and other contaminants (Exhibit 1).
Exhibit 1 Water Desalination Processes
Cost
Because of the amount of energy used and the technology required to produce fresh water from salty water, desalinated water generally is more expensive than many other water sources. Factors such as the depth, location and quality of the source water vary widely and may substantially impact the cost of desalination. The disposal of the concentrated salty waste that is the byproduct of desalination can also be expensive. The TWDB estimates the average cost to produce one acre-foot of desalinated water from brackish groundwater ranges from $357 to $782, while the average cost to produce one acre-foot of desalinated water from seawater ranges from $800 to $1,400.
Since 1989, the TWDB – which provides financial assistance to Texas communities in the form of loans and grants through federal and state programs for water supply, treatment and other water-related programs – has financed 46 desalination projects in Texas with a total value of $612 million.
Desalination in Texas
Desalinated water is a relatively small component of the state’s water supply, but its use is growing. Texas currently has 53 municipal desalination facilities with a combined production capacity of 157 million gallons per day – more than 176,000 acre-feet per year (Exhibit 2). A little more than two-thirds (36%) of the plants treat brackish groundwater and have a total design capacity of approximately 90 million gallons per day (100,769 acre-feet per year). Of the others, 16 treat brackish surface water and one treats wastewater for reuse. Currently, there are no municipal seawater desalination plants in Texas, although Corpus Christi is developing one along the Inner Harbor.
In addition to municipal use, desalinated water plays an important role in certain Texas industries – mainly oil and gas and semi-conductors. The industrial desalination capacity in the state is estimated to be between 60 million and 100 million gallons per day.
Exhibit 2
Largest Municipal Desalination Facilities in Texas
County
Facility
Total Plant Capacity
(millions of gallons
per day)
Water Source
Baylor
City of Seymour
3.0
Ground
Bexar
H2OAKS Center
12.0
Ground
Brazoria
Brazoria County Municipal Utility District No. 21
2.6
Ground
Cameron
Southmost Regional Water Authority
10.0
Ground
Cameron
North Cameron/Hidalgo
2.3
Ground
Cameron
Military Hwy Water Supply Corporation - Las Rusias
2.1
Surface
El Paso
Kay Bailey Hutchison Desalination Plant
27.5
Ground
El Paso
Horizon Regional Municipal Utility District Reverse Osmosis Plant
6.0
Ground
Grayson
City of Sherman
10.0
Surface
Hidalgo
North Alamo Water Supply (Doolittle)
3.5
Ground
Hidalgo
Victoria Road Reverse Osmosis Plant
2.3
Ground
Hidalgo
North Alamo Water Supply (Owassa)
2.0
Ground
Hood
Brazos Regional Public Utility Agency Surface Water Advanced Treatment Systems
15.0
Surface
Hood
City of Granbury
2.5
Surface
Howard
Raw Water Production Facility Big Spring Plant
2.5
Direct Potable Reuse
Karnes
City of Kenedy
2.9
Ground
McCulloch
City of Brady
3.0
Surface
McLennan
City of Robinson Reverse Osmosis Surface Water Treatment Plant
2.4
Surface
Pecos
City of Fort Stockton Osmosis/Desalination Facility
7.0
Ground
Runnels
City of Ballinger
2.0
Surface
Taylor
City of Abilene Hargesheimer Treatment Plant
12.0
Surface
Wichita
Cypress Water Treatment Plant
11.0
Surface
Source: TWDB
Note: Only plants with a capacity greater than 2 million gallons per day are included.
The three largest groundwater desalination plants in Texas are found in Bexar, Cameron and El Paso counties:
H2OAKS Center, Bexar County
Located 17 miles southeast of downtown San Antonio, the San Antonio Water System H2Oaks Center is a desalination, aquifer storage and water recovery facility serving nearly 2 million customers. The desalination plant, which opened in 2017, pumps water from the brackish Wilcox Aquifer and makes it suitable for human consumption by using reverse osmosis and filters to remove the salt.
Southmost Regional Water Authority, Cameron County
The Southmost plant, which serves the Rio Grande Valley, uses reverse osmosis membrane technology to treat previously undrinkable brackish groundwater. The water is pumped from 20 wells drilled into the Rio Grande Alluvium, part of the Gulf Coast Aquifer. Providing more than 40 percent of the area’s water needs, the plant reduces the area’s dependency on the Rio Grande River.
Kay Bailey Hutchison Desalination Plant, El Paso County
Operational since 2007, the plant has the capacity to produce up to 27.5 million gallons of fresh water daily. Through a pressurized process, raw water passes through fine membranes that separate salts and other contaminants from the water. El Paso Water’s plans to expand the plant’s capacity could increase the amount of water produced to 42 million gallons per day.
The state’s largest surface water desalination plant is the Brazos Regional Public Utility Agency Surface Water Advanced Treatment Plant. Located in Granbury, the plant receives raw water through an intake located on Lake Granbury, which is fed by the Brazos River, and uses an ultrafiltration process in addition to reverse osmosis. The Brazos Regional Public Utility Agency was created in 2012, combining the Acton Municipal Utility District and the Johnson County Special Utility District, and directly serves approximately 22,000 customers.
State Water Plan
The TWDB’s 2022 State Water Plan (SWP) contains recommendations for desalination of groundwater, surface water and seawater (Exhibit 3).
Exhibit 3
2022 State Water Plan Recommendations for Desalination
Strategy
Number of Regional
Water Planning Groups
New Water Supply by 2070
(in acre feet)
Share of All Recommended
Water Management Strategies
Groundwater
9
157,000
2.0%
Surface Water
3
63,000
0.8%
Seawater
3
192,000
2.5%
Source: TWDB
Challenges
The process of desalination can be energy-intensive and costly. Although most modern desalination plants use significantly less energy than their predecessors, the energy needed to treat the water – and dispose of the remaining salty waste – remains high.
The environmental impact of the desalination process also is a factor. Pulling saltwater into desalination plants can pose a danger to fish and other marine life, and the disposal of desalination byproducts is also a concern. This is especially true for inland brackish water, where concentrated saline waste usually is injected into deep underground formations. However, some plants are now using evaporation technologies to separate the minerals, which then can be sold commercially.
Some planning groups participating in the SWP did not recommend desalination due to the cost, infrastructure required, and concerns about finding qualified employees in rural areas to operate the sophisticated technology required.
Outlook
According to the Texas Water Resources Institute, desalination currently comprises approximately 1 percent of the world’s freshwater, and its use is growing. Desalination is proving to be a reliable water source that is far less susceptible to natural disasters, drought or depletion than other water sources.
In Texas, desalinated ground and surface water represent an increasing component of the state’s water supply, but there is plenty of room for growth. In 2020, TWDB reported that Texas has more than 2.7 billion acre-feet (880 trillion gallons) of brackish groundwater available in 26 of its major and minor aquifers. That amount of source water suitable for desalination represents a lot of untapped potential.
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