The tender will close on May 20, and construction of the system is expected to start next year and finish in 2027.
The system has been incorporated in new BTO projects such as Punggol Northshore Residences and Tengah town. It is easier to implement rainwater harvesting in new BTO projects because the system's infrastructure can be planned and designed upfront to ensure it is located where the most amount of rainwater can be collected, explained HDB.
"HDB will study the cost-effectiveness of the system in reducing potable water consumption and mitigating flood risks in existing HDB estates, before deciding on the extent of future scale-up to other suitable estates," added the housing board. The system is a key tenet of the 10-year HDB Green Towns Programme, which aims to make existing towns more environmentally sustainable and liveable by cooling them, reducing energy consumption and recycling rainwater.