Writer: Paul Schattenberg

Results from Texas well water screenings in areas affected by flooding over the past few years show the importance of those screenings in helping ensure water quality and human health, said Texas A&M AgriLife Extension Service personnel supporting the agency’s Texas Well Owner Network, or TWON.

“Private water well owners whose wells have been flooded should assume their well water is contaminated until tested,” said Dr. Diane Boellstorff, AgriLife Extension water resource specialist in the department of soil and crop sciences, College Station. “You should not use water from a flooded well for drinking, cooking, making ice, brushing your teeth or even bathing until you are satisfied it is not contaminated.”

flooded paddock and hay bales
After flooding, those with private water wells should assume their water quality has been compromised and have water samples screened for E. coli and other possible contaminants.(Texas A&M AgriLife Extension Service photo)

Floodwater may contain substances from upstream, such as manure, sewage from flooded septic systems or other contaminants. Furthermore, there is no regulation or oversight for private wells, so well owners are independently responsible for monitoring their water quality, she said.

“A septic system near a well also can cause contamination when the well is flooded,” Boellstorff noted. “Well owners need to be concerned with E. coli because its presence indicates well water has been in contact with fecal waste from humans or other warm-blooded animals.”

John Smith, AgriLife Extension program specialist, College Station, said water contaminated with E. coli is more likely to have pathogens present that can cause diarrhea, cramps, nausea or other symptoms in humans.

“Water wells should be tested annually with water samples screened for common contaminants, including E. coli, coliform bacteria, nitrate-nitrogen and salinity,” he said.
Since its inception, TWON has screened water samples from more than 10,000 wells throughout the state.

“As part of our outreach, each year the network offers many well water screenings and educational programs for private well owners throughout Texas,” said Dr. Drew Gholson, AgriLife Extension program specialist and Texas Well Owner Network coordinator, College Station. “These are typically done in collaboration with the local AgriLife Extension office and, in some instances, emergency management personnel. With the amount and extent of flooding we’ve seen in the state over the past few years, we felt it was important and necessary to offer additional screenings in affected areas.”

For example, Gholson said, after Hurricane Harvey, there were additional screenings in 24 counties that had experienced flooding. More than 1,500 private water wells within the affected area were screened.

“We typically find 3-5 percent of well samples tested in our regular screenings are positive for E. coli,” he said. “But about 20 percent of the samples collected and screened from counties affected by flooding from Hurricane Harvey had E. coli. This means the likelihood of E. coli contamination in private water wells affected by flooding can be anywhere from four to seven  times greater than under normal conditions.”

Gholson said such results, as well as those from recent screenings in the Texas Hill Country after that region experienced severe flooding, demonstrate the importance of having well water tested post-flooding.

“From the 18 well water samples from Burnet County we screened, one showed E. coli contamination,” he said. “Of the 77 samples from Llano County, 11 had E. coli contamination, and three of the 30 samples from Mason County were positive for E. coli. In San Saba County, five of 13 samples, or 38.5 percent, showed E. coli contamination. All together, these four counties had 138 well water samples screened, with 20 of them, or 14.5 percent, having E. coli.”

Boellstorff said if a private well owner believes a well might be contaminated by floodwater,  only bottled, boiled or treated water should be consumed until the well water has been tested and found safe. She noted information on decontaminating a well can be found in the AgriLife Extension publications “Decontaminating Flooded Water Wells” and “Shock Chlorination of Wells” on the TWON website.”

“After a flood, well owners should also inspect the well for physical damage and look for signs of leakage,” Gholson added. “If it appears damaged, consult a licensed water well contractor to determine whether repairs are needed. And well owners should also have the well pump and electrical systems checked out.”
For more information on TWON, go to http://twon.tamu.edu.