Unlike carbon block filters that lose as much as 70 percent of their area to the adhesives that hold the block together our carbon has zero adhesives holding it in place. The pore sizes of carbon block based filters are too big to stop any protozoa, bacteria or virus. Yes they filter chlorine and some heavy metals. They basically improve the taste of water without properly filtering out any of the more serious contaminants that can get into water supplies from time to time.