Under sink water filters are another kind of water filters that have become highly coveted over the past few years. Under this category, you will get four kinds of water filters. The under sink water filters from the Shower Filter Store start at as low as $119.95. We have Ultimate Fluoride III with Fluoride, Carbon-KDF and Catalytic Carbon Block Water Filter, H20 Maxi-Flo Inline Under Sink Water Filter, Ultimate Fluoride II Drinking Filter, and Catalytic Carbon Block Under Sink Water Filter.