Water Quality

Aerosol-generating Systems (AGS)

Cooling towers, a type of AGS, are used in many commercial buildings and factories, for comfort cooling or industrial process cooling. When a cooling tower is in operation, water aerosols are emitted from the top of the cooling tower, along with exhaust air. These aerosols may contain Legionella bacteria if the water in the cooling tower is not adequately maintained and disinfected. With such contaminated water aerosols potentially coming into contact with the general public, they could possibly cause serious health issues such as Legionellosis infection.


Registration and Lab Test Result Submissions

The National Environment Agency (NEA) regulates the quality of water in all cooling towers, which will be required to be registered, under the Environmental Public Health (Registrable Aerosol-generating Systems) Regulations 2021 [PDF, 113.2 KB]. The definition of cooling tower can be found in the Environmental Public Health (Registrable Aerosol-generating Systems) Order 2021 [PDF, 81.23 KB]. 

Upon successful registration, owners/occupiers will be required to ensure that the water quality of their AGS complies with the regulatory limits stipulated in the Regulations by arranging for the AGS water to be tested in a testing laboratory accredited by the Singapore Accreditation Council (SAC) and submitting water quality test results to NEA at the frequency stipulated in the Regulations.

The registration and the submission of water quality test results can be submitted electronically via NEA ePortal. Step-by-step user guides can be found as follow:

  1. Step-by-Step User Guide for AGS Registration [PDF, 1 MB]
  2. Step-by-Step User Guide for AGS Lab Test Result Submission [PDF, 602 KB]

The standard excel template for AGS lab test result bulk upload submission can be found as follow:

  1. Standard excel template for lab test results bulk upload submission [XLSX, 22 KB]
Water sampling for a particular month shall be done within the same month, e.g. sampling for September shall be done within the month of September. Water quality test result for a particular month is to be submitted no later than the 14th of the subsequent month. e.g. test result for September should be submitted latest by 14 October. More information can also be found in the FAQ for Aerosol Generating Systems (AGS) Registration and Submission of Water Quality Test Results [PDF, 300 KB].

Updating of Contact Person 

AGS owners should update changes in the particulars of your company or business e.g. company address, contact numbers and emails, etc. via NEA ePortal.

This will allow NEA to share important notifications and reminders and reach you in a timely manner on matters such as water quality test results notifications, inspection outcomes, etc. Without an up-to-date email address and contact details, the AGS owner will not receive these documents and information to carry out the necessary follow-up promptly.

For update of existing email address, please refer to Page 13 -15 of the Step-by-Step User Guide for AGS Registration [PDF, 1 MB].

Code of Practice on Environmental Health (COPEH) 2021

The minimum design criteria for siting of cooling towers at building plan submission, can be found in section 4 of Code of Practice on Environmental Health (COPEH) 2021 [PDF, 699.1 KB].


  1. Guidelines on Cleaning and Disinfection of Cooling Towers for the Control of Legionella Bacteria [PDF, 119 KB]
    Guidance for AGS owners on how to regularly maintain, clean and disinfect cooling towers, as well as situations when water quality is unsatisfactory.