Bangladesh is one of the poorest and densest countries in the world. Approximately the equivalent of half the population of the United States lives in an area the size of the state of Iowa. Similar to other developing countries, more and more people are moving from rural to urban areas to try to make more money. In Bangladesh’s capital city, Dhaka, many of these migrants end up in slum communities which are the most densely settled areas in the country. Dhaka has a population of about 160 million- of these people 32 million do not have access to clean water, 75 million do not have access to sanitation services, the infant mortality is 6 percent and 45 percent live in poverty. Many live on less than $1 a day. Water and sanitation problems arise from poverty, overcrowding, poor housing and inadequate waste disposal. Like urban areas, rural communities are also affected by poor water quality and scarcity. About 90 percent of the population uses groundwater as their primary fresh water source. Sanitary groundwater is becoming harder and harder to find for multiple reasons. In coastal areas, groundwater is salty due to soil desiccation and tidal flooding. Shrimp cultivation is commonly done in large bodies of fresh water which leads to contamination. In addition, climate change and the increase in natural disasters that accompany it can cause damage to water and sanitation infrastructure and threaten the supply of natural resources. A rise in sea level can also cause more communities further inland to be affected by the salinization of groundwater. Even when considering the above mentioned water quality and supply problems, Bangladesh is most severely impacted by the presence of arsenic in groundwater wells. Until the early 1970’s, most people got their drinking water from shallow, hand dug wells, rivers and ponds. Diarrheal diseases and cholera were a problem due to drinking contaminated water. In the late 1970’s, international donors spent millions of dollars digging wells in Bangladesh. The wells had steel pipes with hand pumps that tapped into groundwater in the Ganges floodplain. After the installation of the wells, water related disease mortality did decrease however in the 1990’s many of the wells were found to be contaminated with arsenic. The World Health Organization (WHO) has called the exposure to be “the largest mass poisoning of a population in history.” One article estimates that more than 40 million people have been exposed to arsenic levels up to 1200 parts per billion (ppb), which is 240 times what is considered acceptable by the Bangladeshi government. Bangladeshi government scientists estimated in the late 1990’s that more than 20 percent of the drinking water was contaminated with more than 50 ppb’s of arsenic. problems. Long term intake of arsenic can lead to bladder, kidney, lung or skin cancers, skin disorders, disfigurement, gangrene and heart disease. There are currently no effective treatments for arsenic poisoning however taking certain vitamins can relieve some of the symptoms. A Lancet study followed about 12,000 people residing in Dhaka for ten years and found more than 20 percent of the deaths in this population to be caused by arsenic. The authors explained that even exposure to low doses of arsenic could increase the chance of early death and that damage from the arsenic is most likely permanent. They found that more than 75 percent of the sample drank water contaminated with arsenic above World Health Organization standards.When a well is determined to be contaminated with arsenic concentrations over the national standard, it is painted red which means the community should no longer be using it as a water source. In some cases, all of the wells in a community have been deemed unusable which forces the people to find alternative water sources. Many times the only alternatives are the unprotected water sources used before the wells were installed including ponds or ditches. As a result of this, there has been an increase in diarrheal illness which has especially affected children and led to an increase in child mortality. People will often still use the contaminated wells since their only other alternatives are to use bacteria contaminated sources or to walk long distances to other wells.A 2002 study published in the journal Nature Geoscience focused on research done by MIT scientists who were attempting to determine how the arsenic is getting into the water supply. Using a six square mile test site, they found that organic carbon from shallow ponds dug to provide soil for flood protection sinks in the water, seeps underground and bacteria then digest them, freeing arsenic that was trapped in the sediment. The groundwater then carries arsenic into the wells. Based on their research, they recommended digging deeper wells where there is less arsenic present. Also, they mentioned that rice fields help to filter arsenic from water so building wells under these fields could be another possible solution. Unfortunately, not many can afford to dig wells at the depth recommended. Researchers at Berkeley have also been working on finding effective ways to remove arsenic from the water in Bangladesh and have recently filed two patents. The first involves adding coal ash that has been coated with ferric hydroxide to water. The arsenic will bind to the ash which allows it to be easily filtered out. This would only cost around $2 per person per year. The second solution was developed in 2005 and is based on electrochemistry. The device removes arsenic from the drinking water and besides purchasing the device the only thing required is one D cell battery per person per year. Another option some communities are using is harvesting rainwater in tanks. The limitations to this method are that in the dry season there is inadequate supply and the tanks only hold a limited amount. They are, however, easy to maintain and use. When the tanks are empty, many communities use a traditional way of filtering water, through multiple layers of cotton fabric. In 2010, the United Nations (UN) and the government of Bangladesh announced their goal to provide safe drinking water to all by 2011. Although it was a commendable goal, they far underestimated the extent of those who are impacted by arsenic contamination. The UN, WHO and international donors will be key to determining a solution for the arsenic contamination of water in Bangladesh and action must be taken to not only prevent it from continuing to get in the water supply but also to address the health complications it has caused.