Hydrotech reverse osmosis system installed since 1997. We have pretty decent city water here, but sometimes the chlorine level is too high for my liking. Communities in my area should have a residual free chlorine level of 0.02mg/L at the far end of the supply line, so it's not uncommon to see levels much higher than in our home (though not as bad as in a Swimming pool). . ). Activated carbon pre- and post-filters do an excellent job of removing CL2 (sodium hypochlorite, also known as "bleach”)