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All MCSTs and building owners are responsible for the proper maintenance and security of their water service installations, including water storage tanks. This is to ensure that water conveyed through them is fit and safe for drinking at all times. If not properly maintained, it can be a potential source of widespread contamination.

It is the legal responsibility of MCSTs and building owners to maintain proper annual water tank certification records, closely monitor the deadlines for certification and engage a Licensed Plumber (LP) early. Failure to complete and submit the annual certification in a timely manner is an offence under the Public Utilities (Water Supply) Regulations. The penalty for late certification is a fine not exceeding $10,000 or imprisonment for a term not exceeding 12 months or both.

PUB issues reminder emails to assist MCSTs and building owners with the monitoring of the annual certification. Notwithstanding, you should not wait for our reminder emails before engaging a LP to carry out the work. If you do not receive our reminders and would like to enquire on the certification deadline or update your email address, please click here.

PUB conducts random inspections regularly to ensure that water storage tanks are properly maintained and secured in compliance with the stipulated requirements. These inspections are conducted by a group of Qualified Checkers (QCs) employed by our Contractors (One Centum Pte Ltd and Mei De Engineering Pte Ltd). We seek your cooperation to make the necessary arrangements with our Contractors if the water storage tanks at your premises have been scheduled for a joint inspection.

The maintenance and security requirements of water storage tanks are stipulated in the Public Utilities (Water Supply) Regulations and the SS 636: Code of Practice for Water Services.

Mandatory Annual Inspection, Cleaning, Maintenance and Certification 

Any person responsible for the maintenance of any part of a water service installation having a water storage tank shall engage, at least once every 12 months, a LP to inspect, and where necessary to clean and disinfect, and certify the water storage tank.


  • The water storage tank is fit and safe for the storage of water for human consumption.
  • The water contained in the water storage tank is free from contamination or pollution.
  • Water samples taken from the water storage tanks pass the appropriate chemical and bacteriological examinations.
  • The water storage tank is properly maintained.
  • There is no leakage and no likelihood of leakage in the water service installation, including the water storage tank.

Note: The mandatory annual certification of water storage tanks does not apply to landed residential properties with a water storage tank after the sub-meter. The premises owners are responsible to engage a Licensed Plumber to clean and maintain the water storage tank regularly to ensure that the water is fit and safe for human consumption.

Water Sample Testing

Water samples taken from the water storage tanks are sent to a Singapore Accreditation Council-SINGLAS accredited laboratory for testing of potable water quality to pass the appropriate chemical and bacteriological examinations. Only satisfactory test reports from laboratories accredited by Singapore Accreditation Council-SINGLAS will be accepted. The minimum parameters to be tested and the corresponding typical values they must comply with are shown in table below.


Physical, Chemical & Bacteriological Characteristics Typical Water Quality Values to be Complied With
Physical Analysis Parameters  
Colour (Hazen Unit) <5
Turbidity (NTU) <5
pH Value 7.0 – 9.0
Conductivity (umhos/cm) 80 – 550
Chemical Analysis Parameters  
Residual Chlorine (as mg/l CL2) <2.0
Iron (as mg/l Fe) <0.04 
Bacteriological Characteristics  
Total Colony Count (cfu/ml, 35oC, 48 hrs) <500
E.Coli (cfu/100ml, 35oC, 24 hrs) <1