68e07683_SAHRA___Home_Water_Testing__Likely_source
[Lab result] Mercury [Potential health effects] Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetuses. [Treatment options] Reverse osmosis or distillation systems (POU) [Likely source] 
Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands
SAHRA - Home Water Testing
Likely source