How does Arsenic get into your water?
Arsenic is a natural component in our earth’s crust and widely distributed throughout our environment in the air, water and land. It is highly toxic in its inorganic form.
People are most often exposed to elevated levels of inorganic Arsenic through drinking contaminated water. Often this also results in the use of the same contaminated water in food preparation and irrigation of food crops.
Industrial processes, eating contaminated food and smoking tobacco are among the highest contributors to Arsenic in levels in your body.
Stop smoking it is BAD for you!
The Health Implications of Arsenic
Wikipedia sums it up quite well:
"Arsenic poisoning is a medical condition that occurs due to elevated levels of Arsenic in the body. If Arsenic poisoning occurs over a brief period of time symptoms may include vomiting, abdominal pain, encephalopathy, and watery diarrhea that contains blood.
Long-term exposure can result in thickening of the skin, darker skin, abdominal pain, diarrhea, heart disease, numbness, and cancer.
The most common reason for long-term exposure is contaminated drinking water. Groundwater most often becomes contaminated naturally; however, contamination may also occur from mining or agriculture."
Below is a picture from Wikipedia demonstrating the location with higher Arsenic levels in the ground or soils.
Recommended levels in water are less than 10–50 µg/L (10–50 parts per billion).