All Singapore registered MCSTs and building management agents/owners are responsible to properly maintenance and security of the building /estate 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 the water tanks are not properly maintained, it can be a potential source of contamination. 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.

After cleaning (washing) and Sterilizing of water tank, 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 that comply to the required standards state in accordance to PUB Code of practice SS 636 (Previously is known as CP 48).