Legionella Risk Assessment

Legionella Risk Assessment is the first step in responsible Legionella Risk ManagementAny facility that has a centralized hot water system, cooling tower, hot tub, or decorative fountain should consider conducting a Legionella Risk Assessment. Building owners, healthcare operators and facility managers are responsible for health and safety of their tenants, employees, patients and visitors, which means that they to take the necessary precautions to reduce the risk of exposure to Legionella. This assessment should definitively uncover whether or not a building is at risk for Legionella in cooling towers or other warm water systems throughout the facility. Many reputable water treatment companies offer this service; however, it is important that you do your homework before hiring a company to perform your assessment.

In this role, they must understand how to:

  • Identify and assess potential sources of Legionella
  • Manage any of those potential Legionella risks
  • Take steps to prevent or control any risks
  • Create a Legionella Action Plan to prepare for any potential issues that may arise
  • In the event of an emergency or outbreak, immediately remediate the source of Legionella
  • Record and maintain the any records of Legionella analysis, prevention and remediation
  • Carry out their role in Legionella Prevention

US Legionella Risk Assessment Laws

There is no US Federal Law that governs Legionella Prevention; however, guidance is suggested in and included in The OSHA Technical Manual and multiple other US-based published cooling tower standards. In some cases where it was alleged that no action or not enough action was taken to reasonably prevent and control Legionella, many building owners and operators have been accused of gross negligence in civil cases. In the summer of 2015, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published ASHRAE Standard 188 Legionellosis: Risk Management for Building Water Systems, which is now considered by many to be the definitive tome on Legionella Risk Management in the United States.

Although is it not a law, ASHRAE Standard 188 is a Standard that establishes minimum risk management requirements for buildings with complex water systems. Standards are generally incorporated into building codes over time. Such was the case in New York City during the summer of 2015, when the city saw its worst Legionella outbreak in its recorded history.  In July of that year, the Mayor and Commissioner of the Department of Health and Mental Hygiene enacted emergency proclamations that required building owners to maintain their cooling towers to the standards put forth in ASHRAE Standard 188. Those emergency proclamations were eventually refined and written into law in New York City and New York State. ASHRAE Standard 188 is now part of New York’s Cooling Tower laws, making New York the most progressive state in United States in regard to legionella prevention.

The Risk Assessment Process

A Legionella Risk Assessment is the first step in determining a Legionella water treatment protocol and water management plan. It should include a site survey of the water system and any associated equipment and should be performed by someone who understands the dynamics of complex water systems.

During the risk assessment, it is important to answer the following questions:

  • Is the water is stored in a holding tank or is it re-circulated as part of the overall system? Conventional wisdom has established that particular areas of legionella risk include water tanks, dead legs, dormant shower heads and complex systems of pipe work containing warm water.
  • Is the water temperature in any part of the facility’s water systems between 69°F to 122°F? This is the temperature where almost all strains of the legionella bacteria thrive. Hot water storage tanks should maintain a temperature that is closer to 140°F.
  • Are there potential sources of nutrients in the system that can help bacteria proliferate? Systems that show signs of rust, sludge, scale and/or organic matters tend to have a higher potential for biological growth including Legionella bacteria.
  • Is there a sufficient water treatment program in place? While not all water systems are chemically treated exactly the same way, it is important to note that most warm water systems that are open to the atmosphere are typically treated with some kind of biocide program. This would be true for cooling towers, decorative fountains and hot tubs.
  • Is it possible for water droplets to be produced by the water system, and, if so, can they be dispersed? Cooling tower, showers, Jacuzzi hot tubs, and decorative fountains all have the potential to create an aerosol of water droplets. Microscopic water droplets are easy to breathe in and if they contain Legionella bacteria, they could easily infect a host.
  • Could anyone at the facility be exposed to any potentially contaminated water droplets? Are there workers that take smoking breaks or lunch breaks near a ground floor cooling tower or decorative fountain? Are there patients or residents that could inhale water droplets during a shower?
  • Are there any parts of the water system that are used intermittently or irregularly? Dormant shower heads in sporadically used guest bathrooms could be a huge risk.
  • Is it plausible that any of the tenants, residents, employees or visitors are potentially more susceptible to infection due to age, health or lifestyle? Elderly men and women, very young children, people with compromise immune systems (people who are sick), and people who smoke are at a much higher risk of Legionella infection than non-smokers in good physical condition.

If the assessment concludes that there is no reasonable risk or that the risks are insignificant, and like in the case of New York, it is observed that the water systems are managed properly to comply with the law, the assessment is considered complete. Although nothing further may be required at this point, existing control and prevention methods must continue to be maintained.  Legionella risk assessments should be reviewed regularly; especially when there is reason to believe that it may no longer be valid. For example, in the case where a new water system (like a cooling tower) is added or new plumbing was added to old, a follow up risk assessment should be considered.

If the assessment determines that there is a considerable risk of potential Legionella infection, then the next step should be to have a Legionella Risk Management Program developed for the facility. This is a living document that picks up where the risk assessment leaves off; it defines responsibilities, procedures and ongoing action plans designed to minimize the risk of Legionella at the facility. A Legionella Risk Management Plan is usually incorporated into a total Water Management Plan.

How much does a Legionella Risk Assessment cost?

Pricing for a Legionella Risk Assessment varies depending on the scope of the assessment. A small office building with a typical cooling tower could cost $2000, while a large hospital with hundreds of rooms could cost several thousands of dollars. At Clarity Water Technologies, we perform a preliminary site survey that allows us to provide you with a detailed proposal. In most cases, (assuming reasonable travel time, account size, etc) our preliminary surveys are provided completely free of charge.