Inspecting and Disinfecting Cooling Towers

Building owners are required to hire a qualified person to conduct compliance inspections at least every 90 days that at a minimum incorporate regulatory required elements.

Building owners are also required to enlist a responsible person(s) defined as someone retained by an owner who is capable of making recommendations and diagnosing conditions that require corrective actions, under the guidance of a qualified person to conduct:

  • Routine System Monitoring (at least weekly)
  • Routine System Maintenance (frequency based on manufacturer recommendations and/or industry best practices)
  • Water Quality Monitoring (three times per week, with no more than two consecutive days without measurement)

Water Treatment

Water in a cooling tower system must be treated at least once per day while the system is in operation. Water treatments must include approved oxidizing chemicals and biocides in quantities sufficient to control the presence of Legionella, minimize biofilms, and prevent scaling and corrosion.

Cleaning and Disinfecting

Before starting up a cooling tower system, it must be both cleaned and disinfected. Overall, a cooling tower system must be cleaned at least twice a year. Cleaning and/or disinfection is required whenever an evaluation or sampling results demonstrate microbial concentration at levels requiring corrective actions.

Cleaning usually requires the disassembly of cooling tower components and the use of physical or mechanical methods for the removal of:

  • Biofilm
  • Scale
  • Debris
  • Rust and other corrosive products
  • Sludge
  • Algae
  • Any other potential sources of contamination

Disinfection requires using one or more biocides at a defined concentration, under specific conditions and for an established period to kill or inactivate pathogenic organisms.

The use of biocides requires a commercial pesticide applicator certification in Category 7G- Cooling Towers issued by the NYS Department of Environmental Conservation. You can search an online list of registered pesticide businesses and licensees that are qualified to assist with the disinfection process.

Environmental Sampling

All cooling tower systems must be sampled for the presence of heterotrophic bacteria once a week. They must also be sampled for the presence of Legionella at least once every 90 days.

Legionella samples must be analyzed by a laboratory certified for Legionella culture analysis by New York State’s Environmental Laboratory Approval Program. Any sample results of 1,000 cfu/ml or greater must be uploaded to the Cooling Tower Web Portal within 24 hours of receiving results.

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