Abstract: Tabletized ionene polymers, methods for their preparation and their use in water treatment is described. The tablet contains about 5 to about 60 percent by weight of an ionene polymer, about 40 to about 95 percent by weight of a salt carrier matrix, 0 to about 10 percent by weight of a disintegration rate regulator, and 0 to about 10 percent by weight of an anticaking agent. The tablets may be made by mixing an aqueous solution of an ionene polymer with a carrier matrix to form a moist mass, drying the moist mass to form granules, reducing the granule size to form a powder, and compressing the powder into a tablet. The tablets are useful in a wide variety of water treatment applications. Accordingly, the specification describes a method for controlling the growth of microorganisms in an aqueous system. Using the method, one treats an aqueous system with an ionene polymer in an amount effective to control the growth of at least one microorganism. The ionene polymer is contained in a tablet of the invention.