Sarjan Watertech India Pvt. Ltd. Offers Block Carbon Standalone Filters. Sarjan Watertech India Pvt. Ltd. Has achieved ISO 9001:2000 certifications. Block Carbon Standalone Filters is very common in a number of home water treatment systems. Block Carbon Standalone Filters is used to reduce or eliminate bad tastes and odors, chlorine, and many organic contaminants in municipal [pre-treated or chlorinated] water supplies to produce a significantly improved drinking water. It is also very commonly used as a pre-treatment as part of a reverse osmosis system to reduce many organic contaminants, chlorine, and other items that could foul the reverse osmosis membrane. 0.5 micron carbon block filters are commonly used to remove cysts such as giardia and cryptosporidium.