Prominent industries across Texas and the nation, such as agriculture, mining, manufacturing and health care, depend on clean and reliable water sources to operate. Clean water for households and businesses also promotes public health, a prerequisite for economic growth. [1] Water, however, is a finite resource and is not consistent in its availability. In addition to relying on rainwater, surface water and groundwater, some Texas cities are turning to reusable sources such as highly cleaned effluent and recaptured wastewater.
Water Reuse
Water reuse (also known as water recycling or water reclamation) is the use of wastewater that has been treated to remove contaminants, solids and certain impurities for purposes such as irrigation, drinking water, groundwater replenishment, industrial processes, cooling and environmental restoration (Exhibit 1). [2]
The U.S. Environmental Protection Agency (EPA) does not require or restrict any type of water reclamation, leaving the primary regulatory authority for allocating and developing water resources to state and local governments. The federal Safe Drinking Water Act and Clean Water Act, however, provide a foundation from which Texas can enable, regulate and oversee water reuse. [3]
Exhibit 1 Water Reclamation Glossary
Direct Reuse
Reclaimed water that is piped directly from a wastewater treatment facility to a distribution system for beneficial use. Examples include piping treated wastewater to an industrial center for manufacturing, golf course for irrigation or power plant for cooling.
Indirect Reuse
Reclaimed water is discharged to an environmental buffer watercourse such as a lake, river or aquifer to be used again. Indirect reuse projects that involve a watercourse require a permit that allows the permit holder to convey and subsequently divert water.
Direct Potable
After treatment, reclaimed water is piped directly into the distribution system or blended with the raw water supply before the water treatment plant.
Indirect Potable
Treated reclaimed water is used to augment drinking water supplies by discharging it to a water body, such as surface water, and subsequent treatment for potable consumption.
Rainwater Recovery
Rainwater is captured and stored for landscape irrigation, indoor use and stormwater abatement.
Source: Texas Water Development Board
Direct vs. Indirect Reuse
Indirect reuse of water occurs when wastewater treatment plants discharge water directly into a stream that is diverted and reused by the same permit holder downstream creating, in effect, a closed loop system. Indirect reuse requires special permits that authorize a water rights holder to transmit water back into an open watercourse.
Direct reuse is when water is sent directly from a treatment plant to a location where it is used again without reentering a river or stream. [4] This water can be carried by special pipes (usually colored purple) and used exclusively for irrigation, cooling or certain manufacturing processes. As Texas’ population and household water use has risen, direct reuse has increased as a reliable source of water due primarily to an increase in wastewater flows and the capacity of reuse facilities. [5]
An example of direct reuse is found in the Toyota manufacturing plant in San Antonio – which receives highly treated effluent from the San Antonio Water System through special pipes – for certain industrial processes, such as creating the baths that every truck chassis must pass through. This chemically consistent and temperature-consistent water is available even in the worst of droughts.
Another type of recycled water is advanced purified water – treated wastewater that has been further purified using advanced purification technologies. After water goes through this special purification process, it meets and even exceeds standards for drinking water consumption. [6]
The simplest means of reclaiming water is rain runoff collection. While not defined as reuse in the typical sense, it allows for the use of a resource twice. Typically, this is in the form of rain barrels homeowners and businesses use to collect rain runoff to be used later for landscaping or, on a larger scale, to be incorporated into washing or plumbing that does not require potable water.
Projected Water Supplies
Texas’ water supplies from reuse sources are expected to rise from 620,000 acre-feet in 2020 to 714,000 acre-feet in 2070. Supplies from surface water and groundwater, meanwhile, are expected to decrease from 16.1 million acre-feet in 2020 to 13.1 million acre-feet in 2070, a decline of 18.8 percent (Exhibit 2). Reuse sources as a share of total water supplies are expected to increase from 3.7 percent to 5.2 percent during this period. The rise in reuse supplies will be due primarily to an increase in wastewater flows from a growing population and the capacity of reuse facilities. [7]
Exhibit 2 Texas Annual Existing Water Supply (million acre-feet)
Existing Water Supply by Source, Texas, 2020-2070 (million acre-feet)
Source
2020
2030
2040
2050
2060
2070
Surface water
7.2
7.2
7.2
7.1
7.1
7.1
Groundwater
8.9
7.6
6.9
6.4
6.1
6.0
Reuse
0.6
0.6
0.7
0.7
0.7
0.7
Water Demand
17.7
18.4
18.3
18.4
18.6
19.2
Source: Texas Water Development Board
Purple Piping
In the U.S., purple pipes are used to indicate they are carrying recycled water. The purple pipe distributes treated effluent, primarily for irrigation, but also for non-potable uses such as flushing toilets or some manufacturing processes. [8] Using recycled water provides numerous benefits for Texas such as saving water, protecting the environment and decreasing water waste. Using recycled water through purple pipes means accessing fewer resources from our rivers, streams and groundwater basins and maintains a reliable, locally controlled source of water. [9]
A credit union in San Antonio, Credit Human, has reduced the potable water use in its new 200,000-square-foot office building by 97 percent using San Antonio’s purple pipe network, efficient fixtures and a geothermal heating and cooling system. As a result, Credit Human reports its water bills are about 80 percent lower than for its previous building. [10]
San Antonio Water System (SAWS) has offered rebates and focused on conservation to meet water demand for decades. It has one of the largest purple pipe networks in the country, reusing treated effluent to keep San Antonio’s golf courses green, the River Walk’s river flowing and the Toyota truck plant operating. [11] In Travis County, connecting to the City of Austin’s purple pipe network to supply water to chilling stations, the county expects to save $136,000 and conserve upwards of 10 million gallons (the equivalent consumption of 150 homes) each year. As a result of the savings, the county anticipates covering the programs costs in only eight years. [12]
Water Reuse Facilities in Texas
Texas is home to many successful water reuse infrastructure projects.
Dallas/Fort Worth Metro Wetlands
The 2,000-acre George Shannon wetlands at the Richland-Chambers Reservoir were formed in partnership with Texas Parks and Wildlife to provide clean water for humans and nature.
In 2009, at a cost of $280 million, the North Texas Municipal Water District completed an indirect wastewater reuse program using an 1,840-acre engineered wetland to filter and clean the heavy effluent flows of the Trinity River’s East Fork. After being cleansed by the wetlands, the water is pumped through a 42-mile pipeline back to Lavon Lake, where it is blended and stored until it is sent to the Wylie Water Treatment Plant for treatment as drinking water. [13]
The Bob Derrington Water Reclamation Plant – Odessa
Odessa receives less than 15 inches of a rain a year on average, and its closest major water source is 160 miles away. In 1949, the city began utilizing water reclamation when it purchased land for a wastewater treatment plant under the condition that the seller would receive the treated effluent to irrigate his alfalfa fields. The reuse system continues to the present day and is the longest-running reuse system in Texas. The Bob Derrington Water Reclamation Plant receives approximately six million gallons of wastewater per day, which is used by local industries, fire protection services and irrigation customers. [14]
Blue Hole Elementary – Wimberley
In 2020, the Wimberley School District built Blue Hole Primary School and included in its design the mechanisms to harvest rainwater, air conditioning condensation and grey water (wastewater from showers, baths, sinks and washing machines) to provide water for toilets, landscaping and fire suppression. [15]
Brazos Research Wetlands
Constructed outside Waco at a cost of $2.5 million, this 7-acre wetland was constructed to study and evaluate how endocrine disrupting compounds can be removed from treated wastewater effluent. This innovative approach incorporates a unique combination of surface and subsurface treatment zones, as well as passive aeration units including cascades and turbulent stream channels. The overarching goal is to demonstrate that constructed wetlands are viable treatment components and can be used for indirect potable reuse to produce a new water source in Texas. [16]
Rainwater Recovery
One avenue of water reclamation currently used by some businesses and homeowners is rainwater harvesting. Rainwater harvesting is the capture and storage of rainwater for landscape irrigation, potable and non-potable indoor use and stormwater abatement. Harvested rainwater can be particularly useful when no other source of water supply is available, or if the available supply is inadequate.
It has been calculated that a structure with a 2,000-square-foot roof in a city like Austin (averaging 32 inches of rain per year) could collect up to 34,000 gallons of rainwater per year. In a city like El Paso (8.5 inches of rain per year), about 9,000 gallons might be collected. [17]
While there are many examples of successful rainwater harvesting systems in Texas, in Austin two successes are noteworthy. The Lady Bird Johnson Wildflower Center has a 70,000-gallon rainwater storage tank that supplies 10 to 15 percent of water to the center’s landscape. Additionally, an H-E-B store in Southwest Austin has a rainwater harvesting system with a 28,000-gallon storage capacity that is used to irrigate the location’s landscaping. [18]
Outlook
Water reuse projects provide communities with a new source of clean water while promoting water and energy efficiency and environmental stewardship. Although still a relatively small portion of Texas’ portfolio of water sources, reuse is growing as new technologies emerge to implement conservation strategies that help bolster the state’s water supply.
Endnotes
Links are correct at the time of publication. The Comptroller's office is not responsible for external websites.
Texas Comptroller of Public Accounts, Fiscal Notes, The 2022 State Water Plan, by Spencer Grubbs and Jess Donald (Austin, Texas, July, 2022) (Last visited December 6, 2022). ↳
Texas Water Development Board, “Water Reuse,” (PDF) (April 2019) (Last visited December 6, 2022). ↳
City of Odessa, Texas’ Oldest Living Reuse System Tells All, by Debbie McReynolds (2006); and City of Odessa, “Bob Derrington Water Reclamation Project,” (Last visited December 6, 2022). ↳
