The success of a cross-connection control program is measured by what doesn’t happen.
When your program operates effectively, you identify, protect, test, and maintain hazardous cross-connections before they impact customers or the public water supply. And because the risks are invisible, most consumers never think about backflow prevention.
However, when a failure occurs, the consequences can be immediate, widespread, and costly.
In September 2024, the City of Grand Prairie, Texas, experienced one of the most significant backflow-related drinking water contamination incidents in recent years. Approximately 60,000 residents were affected after firefighting foam entered portions of the municipal water system, resulting in a “Do Not Use” order, extensive flushing operations, emergency drinking water distribution, and a comprehensive investigation.
The incident serves as a powerful reminder that cross-connection control is more than a regulatory obligation, and acts as a critical component of public health.
What Happened?
On September 3, 2024, firefighters responded to a warehouse fire in Grand Prairie’s Great Southwest Industrial District.
Firefighters connected foam suppression equipment to the facility’s fire protection system. At some point during the emergency response, firefighting foam entered portions of the municipal drinking water distribution system.
Residents quickly began reporting unusual tastes, odors, and discoloration in their tap water. As utility personnel investigated the complaints, they confirmed that contamination had entered portions of the potable water system. The City immediately issued emergency notifications and implemented a “Do Not Use” order while crews worked to identify the source and restore water quality.
Although no widespread illness was reported, the incident generated substantial operational and financial burden, and compromised public confidence throughout the community.
The Cause of the Contamination
The investigation identified several factors that contributed to the incident:
- Firefighting foam was introduced into the fire suppression operation.
- The facility’s Fire Department Connection (FDC) was reportedly located upstream of a backflow prevention assembly.
- A check valve intended to prevent reverse flow appears to have failed.
- Emergency operating conditions created circumstances that allowed foam to migrate into the potable water system.
The bottom line? 1) A pathway existed between the hazard and the potable water supply, and 2) protective measures were inadequate, improperly located, or failed. With proactive measures, this failure could have been addressed before contamination occurred.
Fire Protection Systems Require Special Attention
Fire protection systems present unique challenges for cross-connection control programs.
Unlike many standard water service connections, fire systems:
- Operate under unusual pressure conditions
- May remain inactive for extended periods
- Can be modified over time
- Often involve multiple contractors and agencies
- Are utilized during emergencies when normal operating procedures may not apply
Historically, fire suppression systems have caused or contributed to significant backflow incidents because they combine high hazards with infrequent real-world operation. The Grand Prairie incident highlights the importance of evaluating not only routine operating conditions but also emergency scenarios that may create unexpected risks.
Emergency Response Efforts
Once they confirmed contamination, Grand Prairie initiated a comprehensive response that included several critical actions.
- Public Notification: Residents were rapidly informed of the contamination concerns and given guidance regarding water-use restrictions.
- System Investigation: Utility personnel worked to identify the contamination source, determine the extent of the affected area, and understand how the contaminant entered the distribution system.
- Distribution System Flushing: The city conducted extensive flushing operations throughout the water distribution network to remove contaminated water and restore water quality.
- Regulatory Coordination: The city coordinated closely with state regulatory agencies and public health officials throughout the response and recovery process.
- Alternative Water Supply: Hundreds of thousands of bottles of drinking water were distributed to affected residents while the system was being restored.
- Water Quality Monitoring: Ongoing testing verified the effectiveness of corrective actions and confirmed when restrictions could be safely lifted.
The response required professionalism and coordination across departments. It also reinforced a fundamental truth that the most effective response to a backflow incident is prevention.
5 Takeaways for Your Cross-Connection Control Program
1. High-Hazard Facilities Require More Than Initial Approval
Many utilities place significant emphasis on the initial hazard assessment of high-risk facilities and the installation approval process.
But facilities change over time. Equipment is replaced. Operations evolve. Fire systems are modified. Contractors make alterations. Public water systems should periodically review high-hazard facilities to ensure existing protections remain appropriate for current conditions.
2. Verify Actual Field Conditions
One of the most common findings following contamination incidents is that field conditions do not match approved plans or historical records.
Utilities should regularly verify:
- Backflow assembly locations
- Hazard classifications
- Fire system configurations
- Cross-connection protection requirements
Assumptions can become vulnerabilities.
3. Fire Systems Are Not Routine Connections
Fire protection systems require additional scrutiny because they operate under unique conditions. Utilities should evaluate:
- Fire Department Connections (FDCs)
- Chemical suppression systems
- Foam injection systems
- Auxiliary water supplies
- Temporary emergency connections
These systems often present the greatest potential for high-hazard contamination when gaps exist or protection measures fail.
4. Documentation Matters
Following any contamination incident, investigators immediately ask:
- What protection was required?
- Was it installed correctly?
- Was it tested?
- Who approved it?
- Were inspections documented?
Programs with strong documentation can answer these questions quickly and confidently. But programs without adequate records struggle to reconstruct events after the fact and understand the root cause of the incident.
5. Certification Alone Is Not Enough
Perhaps the most important lesson from Grand Prairie is that preventing these incidents requires more than technical certification. Certification programs teach hazard classifications, device selection, testing procedures, and regulatory requirements. But incident prevention requires professionals who can:
- Recognize unusual risks
- Evaluate non-routine operations
- Understand fire protection systems
- Interpret changing field conditions
- Make defensible decisions under pressure
These skills are developed through experience, mentorship, and practical application.
The Bigger Question
The Grand Prairie incident serves as a reminder that cross-connection control is ultimately a public health protection program. Every hazard assessment, inspection, test report, and enforcement action exists to prevent exactly this type of event.
As utility leaders evaluate their programs, the question should must be: “Do we have the knowledge, systems, documentation, and experience necessary to identify and manage risks before they become community-wide emergencies?”
When it comes to cross-connection control, success is not measured by how effectively a utility responds to contamination. It is measured by whether contamination occurs at all.
Ready to learn more about how HydroCorp can support your utility’s cross-connection control efforts?
