Physical limits to fresh water expansion--an emerging reality in many parts of the world--make absolute water scarcity inevitable. The inability of the already developed water supply to meet an ever-growing demand for fresh water also makes the emergence of relative water scarcity unavoidable. Water scarcity--both in its absolute and relative forms--gets accentuated further by an increasing premium attached to water quality and ecological sustainability. The water sector has undergone remarkable changes in recent years. While past achievements were associated mainly with investment in new...