LEGIONELLA: A Rising Threat to Water Management Health & Safety Part 2 - Alliance
November 1, 2016

LEGIONELLA: A Rising Threat to Water Management Health & Safety Part 2

Written by Alliance Environmental

If you have yet to develop a Legionella water management program (plan to reduce the risk of Legionella growth and spread) you may not be certain where, or how to start. In order to fully understand the threat of Legionella in water management systems, it is important to be able to identify what it is, the places it grows, and how it spreads. Legionella can grow in many parts of building water systems that are continually wet. Certain devices can then spread contaminated aerosolized water droplets. Examples of potential growth areas:

  • Hot and cold water storage tanks
  • Water heaters
  • Water-hammer arrestors
  • Expansion tanks
  • Water filters
  • Electronic and manual faucets*
  • Aerators
  • Faucet flow restrictors
  • Showerheads* and hoses
  • Pipes, valves, and fittings
  • Centrally-installed misters*, atomizers*, air washers*, and humidifiers*
  • No steam aerosol-generating humidifiers*
  • Infrequently used equipment, including eyewash stations*
  • Ice machines*
  • Hot tubs*
  • Decorative fountains*
  • Cooling towers*
  • Medical devices* (such as CPAP machines, hydrotherapy equipment,


    *These devices can spread Legionella through aerosols or aspiration.

    There are external and internal factors to buildings that can also cause Legionella growth. External factors include, but are not limited to:

  • Construction: Vibrations and changes in water pressure can dislodge biofilm and free Legionella into the water entering your building.
  • Water main breaks: Changes in water pressure can dislodge biofilm and free Legionella into the water, while dirt and other materials can be introduced into the water and use up disinfectant.
  • Changes in municipal water quality: Changes in water quality can increase sediment, lower disinfectant levels, increase turbidity, or cause pH to be outside recommended ranges. Changes in disinfectant type can impact how you should monitor your program.

Internal factors include, but are not limited to:

  • Biofilm: Protects Legionella from heat and disinfectant; provides food and shelter to germs; grows on any surface that is constantly moist and can last for decades.
  • Scale and sediment: Uses up disinfectant and creates a protected home for Legionella and other germs.
  • Water temperature fluctuations: Provide conditions where Legionella grows best (77°F–108°F); Legionella can still grow outside this range.
  • Water pressure changes: Can cause biofilm to dislodge, colonizing downstream devices.
  • pH: Disinfectants are most effective within a narrow range (approximately 6.5 to 8.5) Many things can cause the hot water temperature to drop into the range where Legionella can grow, including low settings on water heaters, heat loss as water travels through long pipes away from the heat source, mixing cold and hot water within the plumbing system, heat transfer (when cold and hot water pipes are too close together), or heat loss due to water stagnation. In hot weather, cold water in pipes can heat up into this range.
  • Inadequate disinfectant: Does not kill or inactivate Legionella. Even if the water entering your building is of high quality, it may contain Legionella. In some buildings, processes such as heating, storing, and filtering can degrade the quality of the water. These processes use up the disinfectant the water entered with, allowing the few Legionella that entered to grow into a large number if not controlled.
  • Water stagnation: Encourages biofilm growth and reduces temperature and levels of disinfectant. Common issues that contribute to water stagnation include renovations that lead to ‘dead legs’ and reduced building occupancy, which can occur in hotels during off-peak seasons, for example. Stagnation can also occur when fixtures go unused, like a rarely used shower in a hospital room.

    Over the next two weeks, Alliance Environmental Group and Airtek Indoor Solutions will lay out a comprehensive guide to developing, implementing, and evaluating an effective Legionella water management program for your building. Though our assistance is in line with industry standards, it is imperative to follow all relevant federal, state, and local laws, regulations, and ordinances for your specific building.

    For additional information about the growth and spread of Legionnaires’ disease, visit: www.cdc.gov/legionella.

    Alliance Environmental Group, Inc. is a leading environmental contractor in California, with more than 75 years of experience. Alliance Environmental Group and Airtek Indoor Solutions provides innovative resolutions in the areas of: asbestos, lead, and mold abatement; air and

HVAC duct cleaning; heat treatment for pest control; structural pasteurization; demolition and emergency response. The company has successfully completed over 120,000 remediation projects in California and surrounding areas.

For additional information about the company and its services, visit: www.alliance- enviro.com.


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