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Environmental Health Division
Last Updated: 12/08/2022
Community Public Water System Flooding Guidance
What to do now
- Review Flood Resilience: A Basic Guide for Water and Wastewater Utilities (PDF)
- Join MnWARN, a statewide Water/Wastewater Agency Response Network
Days and hours before potential flooding
- Make sure to have enough treatment chemicals on hand to allow for possible delays in access or service.
- Make sure all drinking water storage tanks are full, and ask any interconnected systems to do the same to maximize flexibility in response.
- Shut the electrical power off to the well.
- Wrap and tape well caps with heavy duty plastic to help reduce the opportunity for contaminants to enter the well.
- Once a well is contaminated, it can be difficult to remediate. Some systems have had to seal a well after repeated attempts to remove contamination.
- Protect any electrical or communications wiring or components vulnerable to flooding.
- Sandbag to prevent any breaches to vulnerable critical infrastructure.
During and after flooding
- Call the State Duty Officer at 1-800-422-0798 and say, "My drinking water system has had a [describe flooding incident]."
- The State Duty Officer is a message relay service and will notify the appropriate organizations for response, including the Minnesota Department of Health Drinking Water Protection (DWP).
- DWP will contact you within minutes to discuss the situation, help with technical assistance, and follow through on coordinated response actions.
- Any system can request MnWARN assistance when calling the State Duty Officer.
- Work to keep the distribution system pressurized.
- Once a system loses pressure, it is vulnerable to contamination from intrusion of groundwater, cross-connections and backflow.
- Isolate any breached infrastructure by closing valves to minimize contamination of the rest of distribution system.
- As a general precaution, in coordination with DWP, you may issue a Drinking Water Advisory. If critical infrastructure is breached, you must issue a Drinking Water Advisory.
- The advisory can be limited to the affected area or apply to the entire distribution system if it is vulnerable to contamination.
- Once flood waters have receded, DWP will work with you to get your system back to full operation.
- Once the system is fully pressurized, disinfected, and flushed, DWP will help collect water quality samples to determine when to lift a Drinking Water Advisory.
Learn more at Drinking Water Safety in Emergencies.