Ageing water mains are approaching the end of their service life and have become increasingly difficult and costly to maintain. Upon completion of the replacement and rehabilitation programme in 2015, the maintenance cost of these water mains will be reduced. To replace and rehabilitate these water mains is, therefore, cost effective. As the condition of the water supply network will be strengthened upon completion of the works, the anticipated number of pipe failures per year will be reduced significantly.  The disturbances due to disruption of traffic, loss of trade, inconvenience to  the general public and disruption of water supply to consumers arising from main leaks and bursts will be minimised. Moreover, the loss of treated water through leakage and bursting of water mains will also be reduced.