Security Assessment of Public Water Supplies - EH: Minnesota Department of Health

Security Assessment of Public Water Supplies

While an attack by foreign terrorists may be unlikely, home grown terrorists and ordinary vandals are a threat to the safety of drinking water. The U.S. Environmental Protection Agency requires public water systems serving at least 3,300 people to conduct security assessments. Various organizations offer security self-assessment tools, including the National Rural Water Association. Consider these items: Water Tower: photo courtesy of EPA


  • Ask your local law enforcement staff and public works/utility director to review your security measures.
  • Ask your local emergency manager to review your response plans. Develop mutual aid agreements with neighboring communities for emergency water supplies.
  • Train personnel in security awareness. Post the response actions for reporting threats or acts of terrorism. Call 911 or the local sheriff if suspicious activities occur.
  • Plan for public notification.
  • Practice response plans on a regular schedule.
  • Develop local capacity to communicate with local health care facilities. The Health Alert Network (HAN) is in use by most emergency health professionals.

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Access to Facilities

  • Restrict access with physical barriers to reservoirs, treatment system vents, and intakes. Prohibit parking or stopping on roadways near facilities. Fix all broken barriers, security fences, hatches, and manholes
  • Lock all facilities. Do not leave keys in equipment.
  • Evaluate the reliability and security status of current and former employees. Post “Employee Only” signs at entrances to restricted areas. Tell employees to question any strangers in restricted areas.
  • Store chemicals in secure facilities. Require chemical suppliers to provide their personnel with photo-identification. Use only reliable and known suppliers and contractors. Only accept deliveries of intact containers of chemicals that have been ordered.
  • Install security lighting, motion detectors, and surveillance cameras.

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Access to Documents

  • Limit access to water distribution maps and plans of facilities.
  • Require contractors and consultants to maintain security to their copies of maps and plans.

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Access to Computer Systems

  • Obtain technology security such as firewalls, anti-virus software, and intrusion detection software to protect computer systems.
  • Limit computer access and passwords to personnel who need to know.
  • Join the appropriate Information Sharing and Analysis Center (ISAC): National Council of ISACs.

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  • Keep good records. Discuss unusual events with law enforcement.
  • Ask your local law enforcement officials to routinely patrol facilities and to strictly enforce parking restrictions.
  • Visit all facilities daily.

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Water Disinfection

  • Maintain a free chlorine residual of at least 0.2 parts per million at the ends of the distribution system. If you don’t currently disinfect your system, consider adding a disinfectant.
  • Check chemical quality on a regular basis.
  • Larger systems should consider installation of chlorine residual recorders that will send an electronic alarm if the chlorine residual drops.

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Updated Friday, June 01, 2018 at 08:11AM