Kalgoorlie - Boulder, Western Australia
Not just Kalgoorlie, nowadays it's Kalgoorlie-Boulder, with a current population of 36,000. Boulder had been a seperate town, but the Magic Mile of gold reef was under one side, so that side got shifted to the Kalgoorlie side as the super-pit grew, and they eventually joined together.
Water
It's still hard to believe that a town of 30,000 could exist without a good water supply in the 1890s. It did lead to typhoid and other disease.
There was a government well...