This chapter provides an understanding of the contamination situation in an area. The sampling could be hotspot sampling, blanket sampling, and total screening of samples. Collection and preservation of samples are as important as analysis. Sampling technique is very crucial for the determination of arsenic in water samples. The major concern for sampling and storage are to prevent contamination and minimize the loss of trace amounts of analytes for assessing the total concentration of any element. Several analytical methods are currently used for the determination of total arsenic in water samples. The widely used analytical methods for the determination of arsenic in water are colorimetric/spectrophotometric/silver-diethyldithiocar-bamate (Ag-DDTC) methods, atomic absorption spectrometry (hydride generation and graphite furnace) methods, and inductively coupled plasma mass spectrometry methods. Various clinical, epidemiological, and hydrogeological studies are shown in arsenic-affected areas of West Bengal to determine the magnitude of arsenic contamination and its health effects. © 2009 Elsevier Inc. All rights reserved.