Filtration faucet system

A filtration faucet system for a faucet device having first and second water openings in selectively controllable manner, comprising:

• a filter housing, which is adapted for mounting underneath a faucet countertop, having a filter compartment, a water inlet adapted for operatively linking to a water source, a filtered water outlet adapted for operatively linking to said first water opening of said faucet device, and an unfiltered water outlet adapted for operatively linking to said second water opening of said faucet device;
• and
• a filter cartridge supported in said filter compartment of said filter housing, wherein said filter cartridge is adapted not only for filtering water flowing from said water inlet to said filtered water outlet before said water exits at said first water opening but also for guiding said water directly flowing from said water inlet to said unfiltered water outlet before said water exits at said second water opening, such that said filter cartridge is adapted for selectively filtering and unfiltering said water to said faucet device.