As long as water remains inexpensive and plentiful, water reuse is not a high priority activity for water management. As water becomes more expensive, reclamation and reuse activities gain prominence as an alternative to increasing supplies. In fact, the reclamation and reuse of municipal wastewater is a well-established practice in many areas of the world, and these activities will continue to increase. In many ways, nature's hydrologic cycle provides an excellent model of water reuse and recycling for water managers. For billions of years the Earth has naturally "reused" water through its hydrologic cycle, which continuously cycles water from the sea, to air and land, and back to the sea. * Almost every drop of water that falls on land eventually returns to the oceans. There is as much water on Earth today as there ever was—or ever will be. Thus, every glass of water consumed contains water molecules that have been used countless times before. In this way, all water on Earth can be seen as being reused again and again. In 2008, there are 16 of lodgment & bathhouse, 41 of factory, and 128 of others, 74 of no duty, and Total 259 place in Korea.
It can be Categorized into 3 Class depends on Scale and Usage