TCEQ reviews large cross-connection/backflow response after E. coli detections in major Texas system
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Summary
TCEQ emergency response and optimization staff described a multi-week response to scattered E. coli positives in a large Texas public water system and urged utilities to maintain cross-connection inspection and backflow-assembly test records.
Charlie Middleton of the Texas Optimization Program and Response Team summarized a recent backflow and cross-connection response that involved a large public water system with more than 80,000 connections and daily demand exceeding 50 million gallons.
"A cross connection is any connection to a water supply with to an unknown quality water source or questionable quality water source," Middleton said, describing how both backpressure and backsiphonage can allow contamination to enter a distribution system and how assemblies and air gaps are used to prevent that.
The nut graf: TCEQ's account of the incident stressed the operational difficulty of locating a distributed contamination source when positives are scattered across multiple pressure zones, highlighted that weak recordkeeping hampered rapid triage, and recommended that systems keep current records of customer-service inspections (CSIs) and backflow-prevention-assembly tests (BPATs) so response teams have a reliable starting point if an event occurs.
Middleton described the timeline: an initial E. coli positive was followed by additional positives in August through October, prompting level-2 assessments and a two-week deployment of TCEQ staff and contracted technical teams. Teams inspected treatment plants, tanks and distribution components and ran coordinated CSI teams across the system. While the treatment plants and storage tanks did not show evidence of failure, the response uncovered distribution hazards including unprotected bulk-water filling, untested or missing assemblies, decommissioned tanks that were valved but not air-gapped, and undocumented commercial connections such as informal meat markets. The system elected a temporary conversion to free chlorine to lift the boil-water notice while the response teams continued investigations.
Middleton said the response benefited from assistance from state partners and contractors, but that the lack of comprehensive CSI and BPAT records slowed work. He urged utilities to ensure assemblies are tested annually where required, CSIs are documented by licensed inspectors, and customer-service agreements or local ordinances give utilities the authority to require correction or shut off service for hazards.
Ending: TCEQ advised systems to maintain up-to-date cross-connection inventories, test records and inspection programs and said utilities should consider emergency planning and external technical assistance ahead of incidents.