polymerized salts of polymerizable anionic monomers with cationic germicides are chemically grafted onto activated carbon in a manner to form a permanent , covalent bond thereon . the grafting of such germicides onto the activated carbon imparts permanent bacteriostatic properties thereto and the resulting bacteriostatic activated carbon can be used for the purification of drinking water over prolonged periods of time . the passage of contaminated water across this activated carbon chemically grafted with the polymerized salt of the cationic germicide results in purification of the water which remains free of elevated bacteria counts often associated with &# 34 ; first flush &# 34 ; effluents . mere absorption of such or any germicide into the pores of the activated carbon results in desorption and leaching out of the germicide into the effluent .