This invention is directed to methods of treating inorganic surfaces with aqueous compositions including ionic organosilicon compounds. Surprisingly, it has been found that the application of water soluble ionic organosilicon compounds, which until the present invention have only been used in small quantities to solubilize silanes, to inorganic surfaces provides the treated surface with an excellent hydrophobic property. The present invention exclusively utilizes ionic organosilicon compounds as the main or sole component for imparting water repellency upon surface treatment of inorganic substrates. The methods of the present invention comprise the application of ionic organosilicon compounds to inorganic surfaces whereby imparting water resistance to the substrate. After application, a treated surface may be characterized as having a long term water repellant property.