Reported Cases of "Water Hammering" in Water Pipes

Mr Murali Pillai asked the Minister for National Development (a) whether HDB monitors reported cases by HDB flat owners of "water hammering" in the water pipes; (b) what steps are being taken to minimise such instances of "water hammering" at these HDB blocks; and (c) whether HDB will issue requirements for plumbers to follow when installing water and sanitary fittings in HDB units to prevent such occurrences.

Water hammering occurs in a piping system when water flowing through the pipe is subject to a sudden change in flow direction or forced to stop abruptly. This results in vibration in the pipes which might generate a banging or high-pitched sound and is more common in cases where the water flow rate is high. Water hammering may occur when the water supply to an appliance, for example, certain models of bidets and washing machines, is shut off abruptly, or due to faulty sanitary fittings within the flat or at the common area. HDB does not track water hammering feedback from residents.

To prevent water hammering, at the upstream design stage for HDB flats, HDB's consultants ensure that the water reticulation system is designed for an optimal water flow rate to each dwelling unit. In common areas, Town Councils should conduct regular checks to ensure that the pressure reducing valves (PRVs) installed along the potable water distribution pipes are functioning well with the correct pressure setting.

PUB also encourages households to install more water-efficient fittings to conserve water, and the lower flow rates may help to reduce the occurrence of water hammering. If water hammering occurs due to faulty sanitary fittings within the unit or at the common area, HDB will advise the flat owner or the Town Council respectively to rectify the issue.

Only licensed plumbers approved by PUB are permitted to carry out maintenance work relating to water services and sanitary fittings in HDB flats. Under SS 636 (Singapore Standard on Code of Practice for Water Services), all licensed plumbers are required to inspect water pipes under the stipulated pressure and flow conditions when maintaining or installing these fittings, to prevent occurrences of water hammering.