Water availability and quality must be maintained to assure life on Earth. Sustainability demands we use water judiciously and reclaim the contaminated water. A number of inorganic and organic compounds from arsenic to zinc can pollute our groundwater. Arsenic contamination of groundwater has been affecting around 200 million people worldwide including in the United States; however, it is most pronounced in Bangladesh, where naturally occurring arsenic contaminates millions of wells that were installed to solve the problem of microbial contamination. Arsenicosis, resulting from drinking arsenic-contaminated water can lead to a slow and painful death. To seek viable solutions, workshops were organized by the author in Bangladesh and India, and several symposia were planned at meetings of the American Chemical Society (ACS), UNESCO (United Nations Educational and Scientific Organization), and the International Union of Pure and Applied Chemistry (IUPAC). We need to maintain water quality by monitoring water resources for various known and unknown contaminants rigorously and regularly. Discussion of the problem will focus on how groundwater is contaminated with arsenic, desirable methods for monitoring arsenic contamination at ultratrace levels, and the best options for reclamation. This chapter highlights solutions that offer significant improvements in water purification technologies, at reasonable costs.