Before beginning, make sure the water has been switched off and remove everything from under your sink to create a clear working space.
Disconnect the old faucet from its supply lines using a basin wrench and apply some mineral spirits as necessary if its connections become stuck or frozen.
Removing the Old Faucet
As part of installing a new bathroom faucet, the first step should be removing the old one from its place in the sink. This should be an easy process that anyone with basic plumbing knowledge can carry out themselves.
Underneath your sink should be two water supply lines leading to your faucet: one hot and one cold. Locate both of them. Find their respective shut off valves (which should be clearly labeled) and turn them off to stop receiving water supply.
Use a screwdriver to loosen the screws that secure your faucet, followed by channel-type pliers to dislodge any nuts securing faucet shanks (threaded pipes that extend down from your sink) using channel pliers, before taking steps to set aside these components until later reconnecting them to your new faucet. Finally, be sure to disconnect your aerator to prevent debris from clogging its drain and to avoid debris clog-up.
Installing the New Faucet
Step one in installing your new faucet should be to switch off your water source. You can do this by turning the valves beneath your sink that connect to both hot and cold water lines that feed into it; if unsure where this is located, consult an expert or search online for information regarding your model of faucet.
Once the water has been shut off, you can begin dismantling the old hardware. Locate any nuts holding the faucet to the underside of your sink and loosen them; then pull straight up from underneath your sink until its free from its attachments.
Clean the area around the drain and faucet holes using mineral spirits, clearing away any sealant residue. Some models of faucets include gaskets which should be installed prior to proceeding; others require applying silicone or plumber’s putty in order to create an airtight seal and prevent leakage.
Installing the Handles
Install the handles according to manufacturer’s instructions. In general, most models allow you to simply slide them over a threaded post and tighten them with an included hex wrench. Before beginning work on any handles, be sure to clear out the area beneath your sink, put a bucket under any pipes that might leak, turn off both hot and cold water lines separately as well as loosen any nuts with a basin wrench before twisting off old faucet lines with regular adjustable wrench.
If your new faucet comes equipped with its own supplies lines, connect them to the shutoff valves under the sink before tightening (using hand tightening only) the p-trap nuts (hand tighten). Otherwise, use a tubing bender to adjust each water line so they can pass easily over drain tailpieces in the sink drains.
Installing the Spout
No matter if it is a complete replacement or just an upgrade, having the appropriate tools is key to installing or upgrading a faucet correctly. If you do not own or have access to a basin wrench, buy or borrow one from someone. When dealing with any rusted connections or threaded connections that need loosening up first use penetrating oil to loosen them before trying any more drastic measures.
Once your faucet has been unboxed from its packaging, open both of the shutoff valves under your sink. Remove and install a pop-up drain stopper according to manufacturer specifications for proper installation.
Install the faucet from beneath the sink by threading its tailpieces through mounting holes, tightening locknuts and basin nuts until they click, then tightening them a quarter turn with wrench. For new drain assemblies, apply plumber’s putty around its rim so that it seals tightly against your sink basin rim. Now it is time to reconnect the water supply lines – make sure hot and cold valves match and tighten supply lines manually while tightening them further with wrench.