Water is vital for all known forms of life. Covering 71% of the Earth's surface, it is found mostly in oceans and other large water bodies. 1.6% of the total mass of the Earth's water is below ground in aquifers and 0.001% is in the air as vapor, clouds, and precipitation (rain, snow and sleet).
The Earth's water moves constantly through a cycle of evaporation and transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Over land, evaporation and transpiration contribute to the precipitation over land - thus deforestation and other changes to land can have wide and long-lasting effects through their impact on the water cycle.
Some observers estimate that by 2025 more than half of the world population will be vulnerable to a lack of water. Appropriate water supply and water purification technologies can help.
Underground rainwater storage facilities. Rainwater storage tanks are more important in semi arid areas than any other areas because they are useful in storing limited water supplies for agricultural purposes. In semiarid regions, where precipitation is low or infrequent during the dry season, it is necessary to store the maximum amount of rainwater during the wet season for use at a later time, especially for agricultural supply. One of the methods frequently used is the underground
storage tanks. The in situ technology consists of making storage available in areas where the water is going to be utilised. All rainfall-harvesting systems have three components: a collection area, a conveyance system, and a storage area. In this application, collection and storage is provided within the landscape.
Consider five main factors when designing your underground tank.
- Seepage
- Evaporation
- Length of the dry spell
- Daily usage
- Construction costs
