We further assessed PHREEQC and Reaktoro's performance for bubble point pressure calculations against the experimental data from Bad Blumau, Austria . Originally, hydrocarbon exploration wells were drilled at this site, eventually used for geothermal and balneology purposes. A geothermal doublet, with water being produced at 110⁰C, was established for the spa complex acclimatization. The gas-water ratio is very high, up to 9:1, with the gas phase consisting primarily of CO2 (> 97%). Production logs showed that degassing started at a depth of 560 m. The bubble point pressure can thus be estimated from the hydrostatic pressure at the depth, where the onset of degassing was observed. Considering a brine density of approximately 1065 kg/m 3 , the bubble point pressure is estimated at around 61 bar.