 The reservoir is the source of the Kallang River, the longest river in Singapore.Originally known as the Kallang River Reservoir, Singapore's second reservoir was impounded across the lower reaches of the Kallang River in 1910.In 1922, it was renamed Peirce Reservoir in commendation of the services of Robert Peirce (engineer), who was the municipal engineer of Singapore from 1901 to 1916.