A water filtration system includes a faucet assembly and a filtration assembly. The filtration assembly includes a filter assembly; a filter bracket or mounting assembly for securing the filter assembly to a support surface or structure; and a filter manifold assembly including an unfiltered water inlet for connecting to an unfiltered water supply and a filtered water outlet for connecting to a valve assembly of the faucet assembly. The filter assembly interfaces with the filter manifold assembly to provide filtered water to the faucet assembly under control of the valve assembly. A filter that otherwise would not interface with the filter bracket/mounting assembly and/or the filter manifold assembly can be adapted to work in the water filtration system by using a filter adaptor assembly.