selected from within the range of 1 to 10 by weight of znso 4 7h 2 o so as to be sufficient to impart the desired biological activity an object of the present invention is to provide an antibacterial zeolite material in which an antibacterial metal or metal ion will not elute into any contacting medium whatsoever as a result of which the material exhibits superior antibacterial property safely and for an indefinite period of time a chemical analysis showed that zinc in the clinoptilolite will exchange with calcium ca 2 even though the selectivity of this zeolite is lower for zinc ions however lowering the ph to 1 3 at first step and increasing the ph to 9 11 at the end at the conditions established for the exchange reaction increased the adsorption of the metal zinc into the clinoptilolite structure the release of zinc from the biocide was studied in two different systems 1 a drinking water system and 2 a nacl 0 9 dissolution ph 5 8 to approach a simple biological media fig2 shows the measured performance of the different cations in the exchange process of the biocide when the biocide was placed in a column containing a 20 cm long.