Our Solutions

Solutions to Preventing Legionnaires’ Disease

A higher free chlorine residual, maintained throughout the distribution system, could effectively limit growth of microbes—including biofilm microbes such as legionella and other pathogens—in the distribution system. This level requires a number of strategies and considerations. Simply increasing chlorine at the distribution entry point may result in compliance issues with disinfection by-products.
  • Improve drinking water treatment to reduce organic carbon content. Organic carbon reduction requirements of the Safe Drinking Water Act (SDWA) are frequently violated due to confusion over reporting, lack of enforcement, and scarcity of funding necessary to implement appropriate treatment. These organic nutrients react with disinfectants to form potentially hazardous disinfection by-products, extinguishing the biocidal effect of the disinfectant in the process.
  • Establish chlorine booster stations to reduce the necessary increase at the entry point.
  • Reduce water age (water residence time in the distribution system) by flushing systems, including water storage tanks. High water age is associated with low disinfectant residual.
  1. Require community alerts from the public utility to changes in water supply, planned work, or disruptions to water systems which may release high levels of bacteria into the water.
  2. Regularly test disinfectant levels throughout the drinking water distribution system. Include dead ends and downstream of tanks. Initiate investigation when the required concentration cannot be maintained.
  3. Test drinking water for legionella bacteria prior to it entering a building.
  4. Consider surface swabs for biofilm bacteria testing when lines are open for maintenance.

Former Governor Andrew Cuomo announced during his State of the State address that New York State would be committing two billion dollars to protect drinking water quality. This provides for great opportunity to have a real impact on preventing Legionnaires’ disease as the issue of waterborne pathogen growth in our water systems begins at the treatment plant. Investments in treatment plant upgrades to reduce organic carbon in finished water are necessary to meet water safety goals. These problems are compounded by corrosion and water main breaks in the distribution system. The poor state of water distribution networks is well-known. Many pipes and mains are nearing the end of their service life and require replacement.

The CDC investigation tools call for all potential exposures to be evaluated. Outbreaks are relatively rare and offer an excellent opportunity to increase our scientific understanding of legionella bacteria exposure and dose. In the case of community outbreaks which span multiple buildings, traditional epidemiology frequently causes investigators to disregard sections of the protocol and exclude community water systems as a potential source. The body of evidence for widespread distribution of legionella bacteria from the public water system has grown sufficiently for this mode of exposure to be properly investigated. Thorough use of CDC investigation protocols in outbreaks, including comprehensive water sampling and testing for legionella bacteria, will provide researchers, policymakers, and the public with the best possible data allowing for informed decisions.

It is not sufficient to identify a single water source that contains genetically identical bacteria to patient isolates. Infectious strains of legionella bacteria are endemic to many water distribution systems. If the water supply is colonized then many buildings served by that water supply will also be colonized. Ending an investigation prematurely, such as what happened in New York City, leaves the public at risk.

Critical water quality improvements will take time. Building owners and managers are encouraged to follow best practices related to water management in their buildings. Widespread adoption of the Legionnaires’ disease prevention best practices found in ASHRAE Standard 188 and the CDC Water Management Toolkit.