Bacterial water pollution affects surface water sources to a greater extent. It is most likely in summer
Bacteria and other micro-organisms, among other things, are a common component of surface and groundwater. Many of these are natural, but undesirable micro-organisms can also enter the aquatic environment. In order for water to be consumed without problems, it must undergo a treatment process that removes all harmful substances from the raw water. Unwanted bacteria are most common in surface water sources in the Czech Republic, especially during the summer months. Groundwater is then often contaminated by any polluted sewage or grazing livestock.