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Water Storage Tanks


All management corporations and building owners have to be 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 contamination.

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

Inspection and Certification of Water Storage Tanks

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 licensed plumber 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


The mandatory annual inspection and certification of water storage tanks does not apply to landed residential properties, clustered private housings with water storage tank after the sub-meter etc. 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 is 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 CharacteristicsTypical Water Quality Values to be complied with
Physical Analysis Parameters
Colour (Hazen Unit)<5
Turbidity (NTU)<5
pH Value7.0 – 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