Introduction

Water, Water everywhere, but not a drop to drink. This is a paradox meaning that fresh water fit for use has become scarce. But where has the fresh water gone? The scientific dictum says that matter can neither be created nor destroyed. If this is true then it is sure that fresh water is available aplenty, but we have to find out where it is and how to tap it.

Rainwater

Rainwater is the only source of fresh water. Without rain, all rivers, lakes, ponds, wells etc. will get dried up. The earth will become a desert and all forms of life and plants will whither and die. Sun evaporates water from earth’s surface. This water is sent back as rain or ice. This process goes on perpetually. Although the rate of evaporation is more or less the same in a particular geographical area, it does not rain uniformly. Even a small state like Kerala where the average rainfall is more than 300 cm, different districts get rain at varying quantities. If there is flood in one place, there will be drought in another place. Unfortunately, most of this rainwater flows back to sea or gets evaporated within a short time without percolating to the earth. Then a near drought situation appears immediately after the floods. It follows naturally that in order to survive, we have to tap the rain water according to our increasing needs. A small quantity of water is obtained by constructing dams on the rivers. Some water is collected on wetlands and ponds. This water percolates to the ground. This is called ground water. Most of the rural people depend on the ground water. But when the water is excessively drawn, water level falls further. Nowadays, such ground water is drawn in huge quantities to bottle it for commercial purposes. As a result, groundwater level falls further down making the wells dry. The only way to overcome the water shortage is to harvest rainwater.