Men today are mad after dwelling in cities. Cities have been rapidly expanding both horizontally and vertically. The population in cities has been rising by leaps and bounds. Overcrowding causes too much pressure on natural resources and infrastructure. When cities would be too congested it would not be possible to ensure water-supply to all. No matter how efficient the water-supply system is, with the population rapidly increasing proper water-supply can not be ensured. The per capita water- supply would be much less. Bore wells cannot solve the problem of water-supply. The underground water level would sink further and further down. The reservoirs with limited capacity will fail to meet the increased demand for water. With inadequate water- supply or no water-supply at all life in the city would become miserable.