The Agnano thermal spring water (ATSW) is mainly a salso-bromo-iodic-bicarbonate-alkaline-sulphurous water. Since ancient time, the benefits of thermal spring water in the treatment of various diseases have been known. Today it is known that thermal spring water acts effectively on various physiological and pathological processes such as skin regeneration, respiratory and cardiovascular diseases and bone illnesses and most of these beneficial effects depend on the chemical and physical properties of water. However, all the benefits of thermal spring water may not be fully explained only by its mineral composition. In this regard, it is known that non-pathogenic bacterial populations play an active role in various processes in the ecological and biological fields. The aim of the present study is the microbiological characterization of ATSW through the use of two distinct methods in order to determine the total viable bacterial community.