Water is polluted by leaching from the tailings and acid mine drainage, resulting in several measured sites of bio hazard and radioactivity. Additionally, coal mines in the East side of the area cause acid rain. The water table of Gauteng, of which drink and agricultural water is extracted, is already polluted in some places and is in risk of pollution in others. More important however, is the fact that Gauteng sits at the top of an escarpment that functions as a continental drainage divide. This means that the region is the source of many streams that lead to three big rivers that run through the entire country. If these sources get contaminated, it does not only affect the Gauteng region, but can also have detrimental effects on areas downstream.