Non-revenue water (NRW), poses a very big challenge to many water utilities today. Reducing if not totally eliminating non-revenue water remains the primary concern not only in the Philippines and the Asian region but also world-wide, especially in these times where sources of drinking water supply is rapidly declining. Better and more efficient water supply management is needed to optimize existing water resources by means of reducing the volume of water being lost through pipe leaks, meter under-registrations, illegal connections and other un-authorized withdrawal or use of water from the system. This paper intends to show how Maynilad, the private water operator of the West Zone of Metro Manila (Philippines), has faced its great NRW challenge: to reduce its huge volume of water losses equivalent to 1,500,000 m3/day in 2007, to improve level of service of its existing customers and to supply additional 2.5 million people still without access to piped water. Maynilad’s NRW management team, supported by Miya’s world class experts, has started to get physical and commercial losses in the system under control. The target is ambitious: the volume of NRW shall be reduced by 500,000 m3/day in less than four years.