The Texas Well Owner Network, TWON, will host five events in the South Texas region on May 20-23 to allow residents to have their well water screened.

A “Well Educated” screening will be held in Falfurrias and four “Well Informed” screenings are slated for Benavides, Robstown, Kingsville and Zapata/Rio Grande City.

There is no cost and samples will be screened for contaminants, including total coliform bacteria, E. coli, arsenic, nitrate-nitrogen as well as for salinity.

“The TWON program was established to help well owners become familiar with Texas groundwater resources, septic system maintenance, well maintenance and construction, and water quality and treatment,” said Joel Pigg, Texas A&M AgriLife Extension Service program specialist and TWON coordinator, Bryan-College Station. “It allows them to learn more about how to improve and protect their community water resources.”

Well water contaminants, concerns

A windmill with the sky as a background.
The Texas Well Owner Network, TWON, is holding free well water screenings for residents in the South Texas region, May 20-23. Samples will be screened for contaminants, including total coliform, bacteria, E. coli, arsenic, nitrate-nitrogen as well as for salinity. (Courtesy photo)

John Smith, AgriLife Extension program specialist, Bryan-College Station, said research shows the presence of E. coli bacteria in water indicates waste from humans or warm-blooded animals may have contaminated the water. Water contaminated with E. coli is more likely to have pathogens that can cause diarrhea, cramps, nausea or other symptoms.

The presence of nitrate-nitrogen is also a concern, and water with nitrate-nitrogen at levels of 10 parts per million is considered unsafe for human consumption, he said.

“These nitrate levels above 10 parts per million can disrupt the ability of blood to carry oxygen throughout the body, resulting in a condition called methemoglobinemia,” Pigg said. “Infants less than 6 months of age and young livestock are most susceptible to this.”

Smith added that long-term consumption of arsenic in water increases the risk of skin cancer and cancer in the liver, bladder and lungs. In addition, chronic exposure to arsenic may lead to gastrointestinal irritation and cardiovascular disease. 

Salinity, as measured by total dissolved solids, will also be determined for each sample, he said. Water with high levels may leave deposits and have a salty taste and using water with high levels for irrigation may damage soil or plants.

Sampling instructions

Pigg said area residents wanting to have their well water screened should pick up sample bags, bottles and instructions from their local AgriLife Extension or groundwater conservation district office.

“It is very important that only sampling bags and bottles be used, and all instructions for proper sampling are followed to ensure accurate results,” he said.

Private water wells should be tested annually, and Pigg said it is essential for those submitting samples to be at the appropriate follow-up meeting to receive results, learn corrective measures for identified problems and improve their understanding of private well management.

Funding for TWON is through a Clean Water Act nonpoint source grant provided by the Texas State Soil and Water Conservation Board and the U.S. Environmental Protection Agency. The project is managed by TWRI, part of Texas A&M AgriLife Research, AgriLife Extension and the Texas A&M College of Agriculture and Life Sciences.

To learn more about the programs offered through the network or to find additional publications and resources, visit For more information on the water screening, contact Pigg at 979-321-5946 or

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