Excito under-counter systems remove mechanical impurities, organic contaminants, and some bacteria and viruses. They reduce hardness, the concentration of heavy metals and up to 99% of chlorine, and improve taste and odor. Big Blue 10- and 20-in. housings can be mounted individually or connected in series. They consist of the housing and filter head with a 1-in. brass insert and are equipped with a valve that allows the release of pressurized air accumulated in the filter.