This paper reports the preliminary results concerning the evaluation of the effect of time and storage conditions on some physico-chemical characteristics (pH, conductivity, total dissolved solids and salinity) for 9 mineral waters samples collected from Slănic-Moldova and stored in reusable plastic drinking water bottles. The experimental data show that for the first storage period, respectively 1 month for the samples kept at ambient temperature and 3 months for the samples stored at 4 °C, there were no changes in the analyzed parameters. Significant variations in pH and conductivity were observed after 6 months for 7 out of 9 samples stored at 4 °C and after 3 months for 6 out of 9 samples stored at 20 °C. Also, is noted that the samples stored at 4 °C (in the dark) for 12 months preserved their characteristics better than those stored at ambient temperature for 9 months.