Groundwater recharge through treated wastewater

Water that seeps into an aquifer is known as recharge. Recharge comes from a variety of sources, including seepage from rain and snow melt, streams, and groundwater flow from other areas. Recharge occurs where permeable soil allows water to seep into the ground. Areas in which this occurs are called recharge areas. They may be small or quite large. A small recharge area may supply all the water to a large aquifer. Streams that recharge groundwater are called losing streams because they lose water to the surrounding soil or rock.

Groundwater begins with precipitation that seeps into the ground. The amount of water that seeps into the ground will vary widely from place to place, depending on the slope of the land, amount and intensity of rainfall, and type of land surface. Porous, or permeable, land containing lots of sand or gravel will allow as much as 50 percent of precipitation to seep into the ground and become groundwater. In less permeable areas, as little as five percent may seep in. The rest becomes runoff or evaporates. Over half of the fresh water on Earth is stored as groundwater. As water seeps through permeable ground, it continues downward until it reaches a depth where water has filled all the porous areas in the soil or rock. This is known as the saturated zone. The top of the saturated zone is called the water table. The water table can rise or fall according to the season of the year and the amount of precipitation that occurs. The water table is typically higher in early spring and lower in late summer. The porous area between the land surface and the water table is known as the unsaturated zone

1.0 Introduction
Water is the most essential fuel of life; clean and safe water for daily use is the basic need of human being. Even after decade of hard work and struggle by the govt. bodies & other organization to supply ample amount of potable water to each & every human being in every corner of the world, is not yet achieved. Increasing demand for water, particularly in arid and semi-arid regions of the world, has shown that the extended groundwater reservoirs formed by aquifers are invaluable for water supply and storage. Natural replenishment of this vast supply of groundwater is very slow. Therefore, exploiting groundwater at a rate greater than it can be replenished causes groundwater tables to decline and, if not corrected, eventually leads to mining of groundwater. Artificial recharge as a means to boost the natural supply of groundwater aquifers is becoming increasingly important in groundwater management. Groundwater can have a wide range of beneficial uses. For example, it can be used for irrigation of parks or agricultural land, industrial application, or to provide a potable water supply (i.e. one that is suitable for drinking).

As artificial recharge has increased in popularity, managers have begun to search for additional sources of recharged water. A critical question is whether waters of impaired quality should be used for this purpose, and whether the water recovered from such systems is suitable for potable uses as well as non potable ones. Obviously, water of impaired quality could only be used with appropriate pre and post-treatment, and treatment gained from soil and aquifer processes.

Some factors to consider for Groundwater recharge are;
• Availability of waste water
• Quantity of source water available
• Quality of source water available
• Resultant water quality (after reactions with native water and aquifer materials)
• Clogging potential
• Underground storage space available
• Depth to underground storage space
• Transmission characteristics of the aquifer
• Applicable methods (injection or infiltration)
• Legal / institutional constraints
• Costs
• Cultural / social considerations

2.0 Methodology
2.1 Ground Water
The part of the rainwater, which percolates through the earth’s surface, is known as groundwater. The percolation of the water depends upon the type of substrata. If the substratum is not pervious then the groundwater cannot be conserved as it percolates through the soil below. Groundwater is the major source of drinking water in both urban and rural India. Besides, it is an important source of water for the agricultural and the industrial sector. Water utilization projections for 2000 put the groundwater usage at about 50%. Being an important and integral part of the horological cycle, its availability depends on the rainfall and recharge conditions. The groundwater is stored in different depth zones.