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Our research question was: Will the addition of table salt to the tested sample significantly affect the measured electrical conductivity and pH value of the Kupa River and rainwater? Electrical conductivity was measured with a conductometer, and pH value with a pH meter and an universal pH indicator paper. We measured the pH value of the Kupa river sample once a week, but we measured rainwater when the amount of precipitation was at least 30 ml. To determine whether there were significant differences in the measured values of electrical conductivity and pH values in the salted and unsalted sample, we used statistical tests that showed that the addition of table salt to river water and rainwater significantly affects the measured electrical conductivity, thus not confirming our hypothesis. Also, tests showed that the addition of table salt to the samples did not significantly affect the measured pH value. We believe that this research should be expanded with a larger number of samples from different parts of the world due to the greater reliability of the obtained measurement results and then it could be said whether it is necessary to salt the sample before measuring the pH value.