Rising water demands — and the grim prospect of extended drought — require Texas water planners to look for innovative responses. The 2012 State Water Plan indicates that nearly 40 percent of the water supplies to be developed by 2060 will be the result of conservation and unconventional water sources.27 These include:
- Rainwater harvesting, which typically involves funneling rainwater runoff from roofs or other surfaces into cisterns for storage. Some Texas municipal water systems already provide rebates toward the purchase of rain barrels for capturing runoff.28 Such systems can lower residential water bills as well as the demand for municipal water.
The 2011 Legislature eliminated a legal provision stipulating that rainwater-harvesting systems could be used only for non-potable purposes. Now, captured rainwater can be used for drinking, cooking and bathing, provided the system is installed by a licensed plumber; has a backflow system to prevent contamination of water utility lines; and meets safe drinking-water standards.26
- Aquifer storage and recovery, is the storage of water in an aquifer for later use.29 ASR allows providers to collect surface water and rainwater when it is abundant and store it underground until needed. The San Antonio Water System’s ASR system is one of the nation’s largest, delivering 40 million gallons a day at the peak of the 2011 drought.30 TWDB proposes ASR projects to produce 81,000 acre-feet of water annually by 2060.31
ASR system is one of the nation’s largest, delivering
40 million gallons a
day at the peak of the
- Water reuse, chiefly the use of treated wastewater. In West Texas, reclaimed water has been used in agricultural irrigation for many years. Other uses can include landscaping irrigation, industrial cooling, hydraulic fracturing in natural gas drilling and, with appropriate treatment, drinking water.32 The 2012 State Water Plan proposes a major expansion in reuse, from 100,600 acre-feet in 2010 to 915,600 acre-feet in 2060.33
- Desalination, the conversion of this brackish groundwater into drinking water. Texas has an estimated 2.7 billion acre-feet of brackish groundwater and 44 active groundwater desalination plants, including the world’s largest inland facility, the Kay Bailey Hutchison Desalination Plant in El Paso, which produces almost 85 acre-feet of fresh water daily.34 In all, Texas’ current groundwater desalination plants have a current capacity of about 70,560 acre-feet annually; the Water Plan proposes expanding this total to 181,568 acre-feet by 2060.35
has an estimated
and 44 active groundwater
- Seawater desalination is roughly two to three times expensive than groundwater desalination.36 Although Texas does not yet have a municipal seawater desalination plant, in May 2011 voters in Port Isabel’s Laguna Madre Water District voted to build one on South Padre Island. The plant is expected to cost $13.2 million and will generate about three acre-feet of fresh water daily.37 TWDB proposes a major expansion of the state’s seawater desalination capacity, to 125,514 acre-feet annually by 2060.38
As is often the case with evolving technologies, the major barrier to desalination is cost. The Laguna Madre Water District, for instance, anticipates that building and operating its seawater desalination plant will cost three times as much as a similar plant to treat surface waters from the Rio Grande.39 Nonetheless, desalination offers access to an essentially endless source of fresh water — as long as we can pay for it.