Dissolved minerals, usually measured as total dissolved solids (TDS), are the major determinant of the taste of tap water. The mineral content of drinking water is largely affected by the source water's mineral content, except where membrane treatment removes minerals which then requires remineralization. The aim of this research is to provide guidance to water utilities about TDS differences that allow consumers to differentiate waters and to determine how changing TDS affects the acceptability of drinking water. Panels of consumers and/or trained professionals performed taste tests to determine their ability to discriminate between two water samples with different TDS. Results reveal that to discriminate between waters based on the taste of TDS, a value of approximate to Delta TDS > 150 mg/L is necessary. This provides a baseline target Delta TDS when treating tap water. Panelists provided taste-liking scores, using a 0-10 scale, for individual water samples of varying TDS. Taste-liking scores decreased with increased level of TDS, with an estimated overall rate of -0.23 liking units/100 mg/L TDS. However, there are caveats to this general guidance: specific mineral composition, the direction of change of TDS, the presence of odourants, organic carbon content, temperature, and varying taste abilities and preferences of individual consumers.