What to Do During a Flood Watch



Flood Preparation

  • Have plenty of sample bottles on hand.
  • Check the condition of your field test kits and associated instruments to make sure they work and you have the necessary reagents on hand.
  • Obtain baseline water quality and pressure information. Water quality information should include taste, odor, chlorine residual, turbidity, pH, conductivity, HPCs, etc.
  • Secure access to backup power, generators or other redundant systems. Generators can be critical for keeping the water system running as well as running flood relief pumps.
  • Update distribution system maps and review start-up/shut-down procedures for facilities that may be impacted by the event.
  • Evaluate the services in the potential impact area to evaluate and respond to potential cross-connection concerns.
  • Communicate with fire and police departments about the flood risk to water system infrastructure, related effects on availability of fire flow, and the need for water conservation.
  • Consider sending a notice to customers educating them about the flood and advising them about actions they should consider before, during, and after the flood event.
  • Increase the chlorine residual within the distribution system if feasible.

During a Flood

  • Establish flood boundary conditions as soon as possible.
  • Identify affected pressure zones.
  • Locate emergency sample collection sites within the affected zones and begin collecting investigative samples if possible.
  • Sample for pressure, taste, odor, appearance, pH, conductivity, and chlorine residual. Make quick observation of these results versus the baseline data you collected in preparing for the flood. Are any problems apparent?
  • If you're not able to sample in a flooded pressure zone, increase sampling in adjacent pressure zones/locations. In fact, it's a good idea to take a lot of coliform samples throughout your system throughout the flooding event to get as clear a picture of water quality as possible .
  • If you can't collect all your routine samples in a month when your system is flooded, it will result in a Coliform Monitoring Violation for the month.
  • Consider a health advisory message if the water system appears to be at risk. It may be appropriate to send other messages, such as conservation, curtailment, fire, electrical power, and wastewater concerns at the same time.

Flood Recovery

  • Continue with existing messages until you determine that safe water is available.
  • Coordinate recovery efforts with police, fire, and other utilities.
  • Initiate a coordinated flushing program if a problem is perceived.
  • Identify a number of sampling sites in the affected area.
  • Use a combination of sensory checks (appearance and odor), field tests, and coliform sampling to determine water quality. Collect investigative samples in any zones that flooded as soon as possible and prior to collecting compliance samples.
  • If floodwater entered your distribution system, consider collecting investigative samples from distribution, including coliform, chlorine residual, turbidity, pH, total dissolved solids, VOCs (EPA Method 524.2), and pesticides (EPA Method 525.2).
  • Determine how much technical assistance you can afford and develop guidance documents for your customers as they re-enter the impacted area.
  • Consider disinfection, flushing, sampling, and testing of backflow devices.

Emergency Disinfection of Small Water Systems Publication

Emergency Disinfection of Small Systems 331-242 (PDF) English

Emergency Disinfection of Small Systems 331-242 (PDF) Ukrainian

Emergency Disinfection of Small Systems 331-242 (PDF) Russian

Emergency Disinfection of Small Systems 331-242 (PDF) Spanish

Emergency Disinfection of Small Systems 331-242 (PDF) Tagalog

Emergency Disinfection of Small Systems 331-242 (PDF) Vietnamese

For more information, see Flood Advice for Water Systems 331-300 (PDF) and our Emergency Publications for Water Systems webpage.