A polymeric biocidal salt is prepared from two components. The first component comprises a biocidal anionic or cationic monomeric, dendrimeric or polymeric ion. The second component comprises a dendrimeric or polymeric anion or cation having insignificant biocidal activity and a number average molecular weight of at least about 500. The second component will be cationic in nature when the first component is anionic in nature and anionic in nature when the first component is cationic in nature. The salt is further characterized as partially dissolving when exposed to an aqueous medium, thereby: (a) releasing sufficient biocidal ion to exceed the MIC or MBIC of a target bacteria sought to be controlled; and (b) leaving a reservoir of undissolved salt capable of being further dissolved and releasing additional biocidal ion as the biocidal ion is consumed or is otherwise removed from the environment encompassing the target bacteria.