Water is the abundant natural resource available. Although sea water is the largest natural source of water, it is unfit for domestic use and drinking. Water is essential for survival of all living beings.
Non potable water can be treated to make it potable. The methods are:
- Decantation
- Boiling
- Filtration
- Chlorination
Soft Water
- Forms lather with soap
- Contains less amount of salt
Hard Water
- Does not produce lather with soap
- contain salts of calcium and magnesium
Properties of Water
1. Polar nature - 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.