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.