The dam's actual construction was part of a huge expansion of infrastructure that was begun by the government of the country's first Prime Minister John Molteno (after whom it was later named), who appointed the Cape's first water engineer Mr John Gamble, as well as the mayor David Graaff.
The dam was intended to hold over 50,000,000 gallons of water, in sandy porous clay which presented an engineering challenge from the outset.