In chemistry water is actually an acid and a base albeit weak ones Water is both a weak acid and base because its ionization constant is 10 7 This is how water can create something like the Grand canyon via erosion We usually consider waster to be neutral however in terms of classifying water from a chemical analysis standpoint water has the properties of an acid and a base The following are various definitions of the acid base dichotomy Arrhenius acid generates H in solution base generates OH in solution Br nsted Lowery acid anything that donates a H proton donor base anything that accepts a H proton acceptor Lewis acid accepts an electron pair base donates an electron pair THC Loadee