Koehler Fairfax faucets eventually develop water leaks, like any other faucet, which you can repair yourself without the assistance of a plumber. No matter the configuration of your Kohler Fairfax faucet, you must change out the old, worn plastic valve cartridge for a new one to stop the leak completely.
Before you Begin
As with any other plumbing fixture, before you begin working on your Kohler Fairfax water faucet, you need to shut off the flow of water to the faucet. Failure to do so will lead to water spraying uncontrollably out of the faucet as you remove various parts, and then you will still need to shut off the water to the faucet to avoid serious water damage in your house. You can shut off the water by turning both water supply valves handles clockwise under the sink until they stop. Always turn on the faucet after closing the supply valves to test that no water comes out of the faucet. If water still comes out of the faucet, close the house's main water valve.
Your Fairfax faucet begins leaking when the seals on the valve cartridge fail, no longer providing a watertight seal inside the faucet. When you turn the faucet's water control handle, the handle turns the valve cartridge, changing the flow of water in the faucet. Once the faucet starts leaking water, stopping it requires you to swap out the worn valve cartridge for a new one. The new valve cartridge must look exactly like the original, otherwise the faucet will continue to leak water. Taking the old valve cartridge with you when you go to buy a replacement helps ensure you get the right kind of valve cartridge, helping you avoid an extra trip to the store later.
You must remove the faucet's handle to access the old valve cartridge and install a replacement. If your Fairfax faucet has one handle, you only have one valve cartridge that needs to be replaced. With Fairfax faucets that have two handles, you must first determine which of the two valve cartridges is leaking. Before you shut off the water, place your hand under the spout opening and feel the temperature of the leaking water. If the water leaking out is hot, then you need to replace the hot water valve cartridge. If the leaking water is cold, then swap out the cold water valve cartridge. The handles are held in place by a screw, which sits under a small cap on the top of the handle. Once you pry off the cap, you may remove the screw by turning it counterclockwise with a Philips screwdriver. After you remove the screw, you can then slide the handle off the faucet.
With the handle removed from the faucet, you still must remove other parts before you can swap out the old valve cartridge. Some Kohler Fairfax faucets have a metal domed bonnet piece that sits under the handle, which you must remove next. Other Fairfax faucets have a cylinder-shaped escutcheon piece you must remove. Whichever your faucet has, you can turn them counterclockwise using a pair of pliers with duct tape wrapped around the pliers' teeth at least two times. You then must unthread the mounting nut that sits around the cartridge before finally pulling the cartridge out of the faucet's body.