Citizens across the world are facing a water crisis. The ground water quality had also deteriorated with a 200 ppm increase in total dissolved solids (TDS). Of all the fresh water in the world, only 3 percent is found on the surface of the earth in the form of rivers and lakes. The rest is below the surface, in aquifers, also known as groundwater. Surface water and groundwater are fundamentally different. Water from a river can be recharged in 20 days through rainfall. However ground water is accumulated over a period of hundreds of years as the water percolates through several feet of topsoil, rocks etc. therefore groundwater is ancient water. To give an example, the Great Artesian Basin is an underground aquifer supplying water to Australia. In some parts, the water in the aquifer is nearly 2 million years old..
In India, 90 percent of our drinking water comes from ground water. We are utilizing ground water at an alarming rate compared to the years it takes for that same water to be recharged by natural processes. This is why human intervention like rain-water harvesting is crucial to maintain groundwater levels. We must also remember that ground water is easily contaminated by effluents from polluting industries and household waste. Since the water is deep under the surface, once contaminated it is very difficult to purify.
Safe drinking water is vitally important, it only forms a small part of households consumption. Bathing, laundry and flushing will abound for anywhere between 60 to 70 percent of the water consumed in an Indian home. Apart from drinking water and that used for cooking, all other water leaves the house as waste water through the sewage lines.
Household waste water falls into two broad categories Grey Water (leftover from bathing, hand-washing, mopping floors) and Black Water (waste water that contains human waste including fecal matter). Waste water from laundry is tricky to classify. Laundry water is also the largest source of waste water in a home. Normal detergents used for laundry have high level of phosphates, which means that the water from a washing machine cannot be recycled without prior treatment or filtration. Water from the kitchen sink, after cleaning vessels also requires filtration before in can be recycled.
Of all the fresh water a home receives, roughly 50 percent leaves it as grey water. Grey water recycling offers a huge opportunity for responsible citizens to play their part in solving a global water problem. Even black water can be recycled although it requires several filtration steps to remove the waste. Ironically some lab tests have reported that this recycled sewage water is cleaner and safer to drink than the usual fresh water source.