More than one-third of Delhi's groundwater supply has been found to be contaminated with fluoride and nitrate, which can cause gastroenteritis, fluorosis and skin diseases. Groundwater is used to augment drinking water supply to the Capital's burgeoning population. The presence of these harmful chemicals has been discovered in groundwater sources all over Delhi including South, North, West, Central and East. The Central Ground Water Authority under the Union Ministry of Water Resources has already banned the use of groundwater in Najafgarh area.