5. Water pollution & Water resources in Tamil Nadu

When harmful substances such as chemicals, sewage and waste are dumped into water bodies, contamination occurs. It changes water's physical, chemical and biological properties. It contaminates water and makes it harmful to living beings. Drinking polluted water is dangerous to one's health.

Freshwater resources are water supplies that society can use for household, agricultural or industrial purposes. These include surface and groundwater. Examples of surface water are rivers, reservoirs, lakes and tanks.

There are $17$ major river basins in Tamil Nadu, with $61$ reservoirs and roughly $41,948$ tanks. In Tamil Nadu, lakes and tanks have been employed to collect rainwater during the monsoon and store it for later use. Groundwater sources are called Aquifers.

Aquifers are layers of coarse sand and gravel beneath the earth that contain areas for rainfallcollection. Groundwater can be obtained using open wells and bore wells.