In drinking water or irrigation fields, various dissolved solvents may be present which, depending on their concentration, may be detrimental to human health. An increase in the number of population and industrial and agricultural production are the same time undesirable substances in water. One of such substances that disturbs human health is arsenic, which in human organism can come in different forms. The insreased concentration od arsenic in some parts of the world, as well as in Croatia, it a consequence of natural processes and human activity. Lately, much attention has been paid to determining the concentration of arseni cin drinking water and the development of techniques for its removal, or to reduce its concentration. For this reason, international and national institutions, including Croatia, have adopted laws defining the concentration of arseni cin drinking water and food. The most important guidelines for drinking water quality are World Health Organization (WHO). In Croatia, drinking water quality is prescribed by the Law on Water for Human Consumption (OG 56/13, 64/15) and the Ordinance on Compliance Parameters, Analysis Methods, Monitoring and Water Safety Programs for Water Concervation and the Method of Keeping a Register of Legal Persons Performing the activities of public water supply (OG 56/13, 64/15, 104/17), which is in accordance with the same regulations of the European Union. Entering arsenic into the body via drinking water and food results in increased arsenic concentration in the blood, nails, hair, inactivation of the enzyme, and can also cause cancer.