Water is essential for survival of all living beings. Although sea water is the largest natural source of water, it is unfit for domestic use and drinking. Decantation, filtration, chlorination and boiling are some of the steps that convert non potable water into potable water.

Properties of water make it suitable for use in everyday life for domestic purposes, in agriculture, in industries as coolant and for steam production and in power generation. Water resources are managed by constructing dams, canals, reservoirs, walls. Rain water harvesting can recharge ground water. Human activities are responsible for water pollution.

1. Polar nature of water makes it an excellent solvent.

2. Capillarity: Water moves up from soil through roots and enters the branches and leaves of the plants.

3. Strong surface tension: Upper layer of water acts like a tight sheet and small insects can crawl over and move on the water surface.

4. Density of water is highest at 4°C: This explains why aquatic animals living in water bodies of very cold regions do not die in severe winter.

Increasing population, growth in industries, expanding agriculture and demand for water in thermal and nuclear power plants have pushed up the demand for water. Water conservation by way of rain water harvesting, making dams and reservoirs, recycling of used water and desalination of water has become the need of the hour.