Natural disasters are one of the biggest threats to public health. Floods account for about 40% of all natural disasters that are happening around the world, and are probably the most common natural disaster. They are extremely important for public health because of the many adverse health effects on the affected population. Floods create conditions that include an increased disease transmission rate, including zoonosis frequently transmitted to humans, and increased incidence of diseases transmitted by vectors. They also cause problems with contaminated and/or interrupted water supply and sewage, compromised sanitation and hygiene caused by migration of people and overcrowding, and disrupted public health. The increase in mortality rates during the floods are partly caused also by injuries. Very often floods lead to technical failures that result in the discharge of hazardous substances and thus the primary contamination of drinking water with infectious material or chemicals causing infectious diseases and reducing the quality of water, and secondary contamination of soil and homes. Damp buildings can become an ideal hotbed of mold and bacteria whose secondary metabolites can endanger human health. Consequences of flooding could lead to development of neurotic disorders and psychosomatic disorders, and frequent absences from work. We live in an age of climate change, which cause weather extremes that lead to flooding. The incidence and destructiveness of floods will increase and become more significant problem for public health.