Singapore Polytechnic


To provide an underground tank facility for collection, filtration, retention, and recycling of rain water that is both functional and aesthetically pleasing at the “Ecoasis”.


A pit was excavated according to project requirements to accommodate VersiTank® to be installed in two layers. The base of the pit was compacted and leveled with a layer of coarse sand and an impermeable HDPE liner installed to form a retention tank. An outlet pipe leading to a sump was inserted just above the pit base. An overflow outlet leading to a discharge drain and a pump linked to a conveniently positioned tap are located in the sump.

Assembled VersiTank® units were positioned in two layers within the tank and completely enveloped with permeable geotextile fabric overlapped by 200 mm where they connect. The geotextile was topped with 200 mm of coarse sand and decorative pebble rocks spread on top. Planting at the periphery of the tank completed the installation.

The rainwater harvesting facility provided by this VersiTank® installation demonstrates how the twin concepts of Sustainable Building and Sustainable Living are put into practice by this educational institution – improving its water efficiency by providing water for irrigation and general washing and contributing to stormwater management by offering filtration at source and also helping to reduce peak flows during heavy rainfall.