It is well known that alcohol beverages are mainly composed by the two core water and ethanol components. 1-propanol and 2-propanol, which are the so called ethanol congeners, change the physicochemical properties of the binary (water + ethanol) liquid mixture, when present even at small concentration. New accurate density values were obtained for the ternary (water + ethanol + 1-propanol) and binary: (water + ethanol); (water + 1-propanol) and (ethanol + 1-propanol) liquid mixtures, at 293.15 K and 0.1 MPa. Three-dimensional representations of the excess molar and partial molar volumes are presented and interpreted in terms of H-bonding, packing, branching and hydrophobic/hydrophilic balance. The branching effect was assessed by the comparison with the ternary system where 1-propanol is substituted by its bulkier isomer 2-propanol. (C) 2019 Elsevier Ltd.