Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems
04 November 2009
Groundwater is water that exists beneath the earth’s surface in underground streams and aquifers. An aquifer is a geologic formation of sand, soil and gravel where groundwater is stored – it is deposit of groundwater that can be used sustainably as a water source by humans.
It can take tens of thousands of years before groundwater is discharged in the form of a spring, or it may flow into rivers and vleis. This water has an important ecological function on which many vleis rely. According to hydro-geologist Roger Parsons “Groundwater ….. flows from the ground into rivers during their low-flow periods, and then from rivers back into the groundwater during higher-flow periods”. Other groundwater dependant ecosystems, e.g. in the Table Mountain group, include; plateaus with deep sandy soils; wetlands in the mountains and river valleys; caves; etc.
Boreholes, however, tap into the groundwater supply, and if not controlled properly this water source can be over-exploited resulting in the drying up of the supply. Prior to the drying up, a borehole user may experience a drop in yield due to a diminishing water level. Drilling deeper may result in increased supply but again this supply may dry up if the usage is not managed. The result over time could be irreversible damage to the surrounding eco-system due to over abstraction.
It would be far better to utilise wasted grey water that the majority of households send to the water treatment works along with their effluent each day. Not only does this excess grey water place a too great a burden on the sewerage treatment plants, resulting in untreated effluent that is discarded into our rivers, but its usage would ensure the sustainability of our precious groundwater supplies and the protection of our ecology.