Cooling Tower Cleanings

Cooling tower cleanings and disinfections are required by NYC DOHMH. Metro Group’s trained technicians will complete this two day process by adding the proper dose of disinfecting chemical, surfactant, and anti-foaming agent on day one. After allowing the chemicals to circulate for 24 hours they will drain the tower, physically clean all wetted surfaces, and refill the tower. All cooling tower related condenser piping should also be drained and flushed, which can be completed for an additional charge.

Effective May 7, 2026, NYC Department of Health and Mental Hygiene (NYC DOHMH) adopts new cooling tower requirements under Local Law 159 of 2025 (LL159) building upon Local Law 77 of 2015 (LL77) to strengthen public health protections and further reduce the risk of Legionnaires’ disease.

View NYC DOHMH Notice of LL159 Adoption here.

Selective Key NYC DOHMH Regulatory Changes from LL77 to LL159 (Not Exhaustive):

• Legionella sampling must not exceed 31 days while the system is in operation
  (previously every 90 days) (page 8, § 20-3, April 2026)
• Legionella samples must be analyzed by a NYS ELAP–certified laboratory
  (previously NYS ELAP–certification was not required) (page 8, § 20-3, April 2026)
• Post Hyperhalogenation Legionella Sampling must occur within 31 days of completion
  (previously 45 days) (page 6, § 13-4, April 2026)
• Electronic notification of Cooling Tower System Startup and Shutdown is required within 5 days
  (previously did not have to report electronically) (page 11, § 25-a and b, April 2026)
• Hefty Increases to the fine schedule
  (doubled penalties for both first-time and repeat violations) (page 13-15, § 29, April 2026)

These updates increase responsibility for building owners and raise the risk of violations if programs aren’t updated on time.

Metro Group is NYC’s leading cooling tower compliance expert, providing end‑to‑end support through our certified specialists and in‑house CDC ELITE and NYS ELAP‑accredited laboratory.