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Water Quality After Extended Closure

Ensure the safety of your building water system and devices after a prolonged shutdown

El Toro Water District continuously monitors the drinking water quality throughout its system to meet or surpass all Federal and State regulations. While the District monitors more than 170 miles of pipeline, it cannot monitor the water after the water meter and throughout commercial properties. Typically, this isn’t an issue as water is utilized quickly after it passes the meter. However, since many buildings have been closed, the drop in building water use increases the risk for biological growth within the building plumbing and associated equipment like cooling towers, pools, decorative fountains, hot tubs, and other equipment. During this period, it’s likely that water flow has slowed or stopped throughout portions of the building. This stagnation could lead to a loss of a chlorine residual within the water, which is a significant factor that allows bacteria such as Legionella to grow. If Legionella grows during low-use periods, building residents have a higher risk of contracting Legionnaires’ disease as they return to work.

The District recommends following the Center for Disease Control’s Guidance for Building Water Systems listed below.

8 Steps to take Before Your Business or Building Reopens

1. Ensure your water heater is properly maintained and the temperature is correctly set

  • Determine if your manufacturer recommends draining the water heater after a prolonged period of disuse. Ensure that all maintenance activities are carried out according to the manufacturer’s instructions or by professionals.
  • Make sure that your water heater is set to at least 120°F
  • Higher temperatures can further reduce the risk of Legionella growth, but ensure that you take measures to prevent scalding if you water heater is set to >130°F

2. Flush your water system

  • Flush hot and cold water through all points of use (e.g., showers, sink faucets)
  • Flushing may need to occur in segments (e.g., floors or individual rooms) due to facility size and water pressure. The purpose of building flushing is to replace all water inside building piping with fresh water.
  • Flush until the hot water reaches its maximum temperature

3. Clean all decorative water features, such as fountains

  • Be sure to follow any recommended manufacturer guidelines for cleaning
  • Ensure that decorative water features are free of visible slime or biofilm
  • After the water feature has been re-filled, measure disinfectant levels to ensure that the water is safe for use

4. Ensure cooling towers are clean and well-maintained

  • Ensure that cooling towers are maintained (including start-up and shut-down procedures) per manufacturer’s guidelines and industry best practices
  • Ensure that the tower and basin are free of visible slime or biofilm before use
  • If the tower appears well-maintained, perform an online disinfection procedure
  • Guidance on disinfection procedures from the Cooling Technology Institute: http://www.cti.org/downloads/WTP-148.pdfpdf iconexternal icon

5. Ensure safety equipment including fire sprinkler systems, eye wash stations, and safety showers are clean and well-maintained

  • Regularly flush, clean, and disinfect these systems according to manufacturers’ specifications.

6. Ensure hot tubs/spas are safe for use

  • Check for existing guidelines from your local or state regulatory agency before use
  • Ensure that hot tubs/spas are free of visible slime or biofilm before filling with water
  • Perform a hot tub/spa disinfection procedure before use
  • CDC Guidance (follow Steps 4–9 and 12–13): https://www.cdc.gov/legionella/downloads/hot-tub-disinfection.pdfpdf icon
  • Facilities may decide to test the hot tub/spa for Legionella before returning to service if previous device maintenance logs, bacterial testing results, or associated cases of Legionnaires’ disease indicate an elevated level of risk to occupants. All Legionella testing decisions should be made in consultation with facility water management program staff along with relevant public health authorities.

7. Maintain your water system

  • Consider contacting your local water utility to learn about any recent disruptions in the water supply. This could include working with the local water utility to ensure that standard checkpoints near the building or at the meter to the building have recently been checked or request that disinfectant residual entering the building meets expected standards.
  • After your water system has returned to normal, ensure that the risk of Legionella growth is minimized by regularly checking water quality parameters such as temperature, pH, and disinfectant levels.
  • Follow your water management program, document activities, and promptly intervene when problems arise.

8. Develop a comprehensive water management program (WMP) for your water system and all devices that use water. Guidance to help with this process is available from CDC and others.

If you have any questions, please call the ETWD Customer Service Team at (949) 837-1660.