How to Install an Under-Sink Water Filtration System

Install an under-sink water filter by connecting it to your cold water line with included fittings, mounting the filter housing under the cabinet, and installing a separate faucet if needed.

  1. Kill the Flow First. Shut off the cold water supply valve under the sink by turning it clockwise. Turn on the cold water faucet to drain any remaining water from the line. Clear out the cabinet space under the sink and lay down towels to catch any water spills during installation.
  2. Scout Your Spot. Select a spot on the cabinet wall or back panel where you can securely mount the filter housing. Ensure there's enough clearance above the filter for cartridge changes and that water lines can reach without kinking. Mark the mounting holes with a pencil.
  3. Anchor the Bracket. Drill pilot holes at your marked locations using a drill bit slightly smaller than your mounting screws. Attach the mounting bracket to the cabinet wall using the provided screws. Make sure the bracket is level and can support the weight of the filled filter housing.
  4. Tap the Main Line. Locate where the cold water line connects to the faucet under the sink. Disconnect this connection and install the provided T-fitting or valve adapter. Connect one end to the original faucet line and the other to the filter input line using the compression fittings provided.
  5. Route the Clean Water. Connect the filter output line to either your existing faucet or to a separate filtered water faucet. If installing a separate faucet, drill a hole in the sink or countertop using a hole saw, then mount the new faucet and connect it to the filter output.
  6. Secure All Fittings. Hang the filter housing on the mounting bracket and connect both water lines to the filter. Hand-tighten all connections, then use a wrench to snug them an additional quarter turn. Don't overtighten as this can damage the fittings.
  7. Verify No Leaks. Turn the cold water supply back on slowly. Check all connections for leaks and tighten if necessary. Run water through the system for several minutes to flush the new filter cartridge. Check the manufacturer's instructions for initial flushing time, typically 5-10 minutes.