Water is called life, but it can be also the reason of death when it get contaminated with arsenic. 

Water pollution is a natural problem which can be the result of waste of food, human and animal waste, industry, agriculture, or fishing etc.
Water pollution can be divided into two categories 

A)Surface water pollution
B) Ground water contamination

Surface water pollution
Source: chemical pollutants,sewage water, household sewage,fertilizer, insecticide, pesticide,religious or cultural congregations

the main risk of Ground water contamination is the arsenic pollution.

What is Arsenic?
Arsenic is a metal and natural part of the earth found in water that causes the arsenicosis.
People of Bangladesh were much dependent on ground water for drinking and irrigation purposes as well. before the discovering of Arsenic, groundwater was considered safe for drinking. An estimated 97% of drinking water of the rural population in Bangladesh is now supplied by groundwater.

The World Health Organization (WHO) has given a proper guideline value of 0.01 mg/l for total arsenic in drinking water.
The Government of Bangladesh has also set a guideline water quality standard of 0.05 mg/l arsenic for drinking water.

Arsenic poisoning takes many years for the effects of drinking arsenic
contaminated water. Evidence of chronic arsenic toxicity is accumulating and includes melanosis , hyperkeratosis of palm and sole, gangrene and skin cancer.
Malnutrition and hepatitis B, both of which are prevalent in Bangladesh, accentuate the effects of arsenic poisoning.

Solutions can be like this :

Identification of safe tubewells
Groundwater treatment
Treated surface water
Use of hand-dug wells in reducing aquifers
Rainwater harvesting