Prediction of phase equilibrium for multicomponent systems containing associating compounds (e.g., water and alcohols) is essential in a number of engineering applications (e.g., environmental technology, gas hydrate inhibition) and at the same time represents one of the most stringent tests for a thermodynamic model. Conventional models (e.g., cubic equations of state and excess Gibbs free energy models) provide rapid and often reliable estimates of phase equilibrium in many cases but extension to multicomponent systems, especially those containing water is often troublesome. On the other hand, novel association equations of state perform considerably better but are slower compared to conventional models. Furthermore, the extension of several of them to cross-associating systems (e.g,, water-alcohols) exhibits problems, in this work, the performance of two well-known conventional models (SRK and NRTL) is compared for multicomponent systems to a recently proposed association equation of state both in terms of accuracy of predictions and timing. The proposed model incorporates the Wertheim chemical association theory (employed previously in models such as SAFT) and the SRK equation. The model is applied in this work to multicomponent systems in such a way that the inclusion of the Wertheim theory does not give execution times much higher than conventional models. The model yields very satisfactory predictions of multicomponent equilibria for aqueous (both vapor-liquid and liquid-liquid equilibria) systems containing methanol, gases and hydrocarbons, which are moreover, as will be demonstrated in this work, considerably better compared to SRK and NRTL.