https://www.channelnewsasia.com/singapore/pub-reservoir-water-bidadari-housing-underground-land-scarce-grace-fu-4419016
Singapore completes first underground service reservoir, located under Bidadari park - CNA
The surface footprint of the Bidadari Underground Service Reservoir is about a third of the area taken up by a typical service reservoir of similar capacity.
service reservoirbidadari parksingaporecompletesfirst