The reclamation of water from waste-water in a planned or unplanned manner is known as Water Reuse.
The waste or excess water from any system can be treated and reused.
Types of Water Reuse
This treated water can be used for watering plants,cleaning and washing, irrigation, recharging groundwater, filling up swimming pool or garden ponds and even for drinking.
If the water is reclaimed for potable purpose then the process of reuse can be seperated into three different strategies :
1.Indirect Potable Reuse(Planned) :
"The reclamation and treatment of water from wastewater
(usually sewage effluent) and the eventual returning of it into the
current/natural water cycle well upstream of the drinking water
treatment plant. Planned reuse indicates that there is an intent to
reuse the water for potable use."(Source)
2. Indirect Potable Reuse(Unplanned) :
The treated waste-water often inadvertently get injected into the natural sources of water like pond,streams,lakes etc. and later this sources are utilized for making drinking water. This unplanned reclamation of water is referred as Indirect Unplanned Potable Reuse.
3.Direct Potable Reuse :
"Direct Potable Reuse can be defined as either the injection of recycled water directly into the potable water supply distribution system downstream of the water treatment plant, or into the raw water supply immediately upstream of the water treatment plant."(Source) That means consumer of such kind of supply system receives slightly diluted or undiluted recycled water.
Water Reuse Potential
The potential of water reuse, which is the amount of water that can be reused from waste-water, will indicate the potential of reused water to reduce or mitigate the water demand from any system.Thus reducing the load on the natural water sources which is nowadays becoming scarce due to climate change and uncontrolled use of ever-growing population.
That is why "more" you reuse water "more" you reduce wastage of water and "more" you conserve water for future reuse.
Water reuse is one of the most talked about mitigation measure to counter the impact of climate change on availability of water resources.