How to Replace a Bathroom Sink Faucet?

Replacing a Bathroom Sink Faucet is one of the most practical upgrades you can do in a restroom renovation. A new faucet improves daily control, reduces leaks, refreshes the look of the vanity area, and can simplify cleaning around the sink deck. The job is very manageable with standard tools, but success depends on planning around the existing sink hole pattern, supply line condition, and the space available under the basin. This guide walks through the full replacement process from removal to final testing, with product reference based on COIGN’s single lever basin mixer.

Before You Start: Confirm Compatibility and Gather Tools

A smooth replacement starts with the right match between faucet and sink.

Key checks:

• Hole count and spacing
  Many bathroom sinks are single-hole or widespread configurations. Confirm whether your new faucet is designed for your hole pattern, or whether you need a deck plate.

• Mounting method
  Most modern single-lever mixers mount through the sink deck or countertop with a threaded shank and mounting nut.

• Supply line condition
  If flexible hoses are old, stiff, or corroded, replacing them during the faucet swap reduces leak risk.

• Shutoff valves
  Verify the angle stops under the sink turn smoothly and fully close. If they cannot shut off water reliably, address that before the faucet change.

Tools and materials:

• Adjustable wrench or basin wrench
• Screwdriver
• Bucket and towels
• Flashlight or headlamp
• Plumber’s putty or a suitable sealant if required by the sink material
• New supply hoses if needed
• Thread seal tape only for threaded pipe connections when appropriate, not for compression fittings

If the work area is tight, a basin wrench is the single most helpful tool because it reaches mounting nuts behind the sink bowl.

Step 1: Shut Off Water and Prepare the Work Area

Start with safety and control. Water under pressure can turn a simple swap into a mess quickly.

1. Close the hot and cold angle stops
   Turn clockwise until fully closed. If one valve does not close, stop and repair or replace the valve before proceeding.

2. Relieve pressure
   Open the faucet and let water drain. This also confirms the shutoff valves are working.

3. Protect the cabinet and floor
   Place a towel under the valves and a bucket beneath the supply connections. Small amounts of trapped water usually drain when hoses are removed.

4. Disconnect power if relevant
   If you have a nearby outlet powering an accessory, keep cords away from the wet area.

At this point, you should have a dry, controlled environment to work in.

Step 2: Disconnect Supply Lines and Remove the Old Faucet

Removal is usually the most time-consuming part because of corrosion and limited space.

1. Disconnect supply hoses from the shutoff valves
   Use an adjustable wrench to loosen the nuts. Hold the valve body steady with another wrench if needed so you do not twist the plumbing.

2. Disconnect the faucet hoses or shanks from below
   Some faucets have integrated flexible hoses that pass through the sink. Others have rigid shanks.

3. Remove the mounting nut or mounting plate
   Use a basin wrench if space is tight. If the nut is stuck, apply penetrating oil and wait a few minutes.

4. Lift the old faucet from above
   If it is stuck to the sink deck due to old putty or mineral buildup, gently rock it and use a plastic scraper to break the seal.

5. Clean the sink deck thoroughly
   Remove old putty, sealant, and mineral deposits so the new faucet base sits flat. A flat seating surface is critical to prevent wobble and water intrusion.

If the old faucet left stains or a ring mark, cleaning now improves final appearance and prevents the new base from sealing unevenly.

Step 3: Prepare the Sink Holes and Dry-Fit the New Faucet

Dry-fitting prevents surprises during installation.

• Confirm the faucet shank clears the sink hole cleanly
• Check that the handle has enough rear clearance from the backsplash
• Test the deck plate alignment if you are using one
• Confirm the gasket sits flat and covers the contact area evenly

If the sink has three holes and the new faucet is single-hole, a deck plate is often used to cover unused holes. The goal is a clean surface with no gaps where water can seep into the vanity top.

COIGN’s single lever basin mixer is designed for modern bathroom layouts and streamlined installation, which helps installers keep the top-side appearance clean and reduces under-sink assembly complexity.

Step 4: Install the New Single Lever Basin Mixer Securely

Mounting must be tight enough to prevent rotation, but not so tight that it damages the sink or distorts gaskets.

1. Install the faucet from above
   Feed hoses through the sink hole, align the base, and hold it in the desired position.

2. Install the mounting hardware from below
   Add the rubber gasket and metal plate if included, then thread on the mounting nut.

3. Align the faucet precisely before final tightening
   Stand above the sink and confirm the faucet is centered and straight.

4. Tighten gradually and evenly
   Use a basin wrench or deep socket where appropriate. Tighten until the faucet is rigid and does not rotate under hand pressure.

5. Check the base seal
   If your model uses a gasket, ensure it is compressed evenly. If a sealant is required for your sink surface, apply it sparingly so it does not squeeze out visibly.

A properly mounted faucet should feel solid with no movement when you operate the handle.

Step 5: Connect Water Supply Lines Correctly and Avoid Leaks

Most leaks come from improper connections, overtightening, or reusing old hoses.

Connection best practices:

• Use new supply hoses when the old ones show wear
  Fresh hoses reduce the risk of hidden cracks and simplify tightening.

• Do not use thread seal tape on compression hose connections
  Compression fittings seal by compression, not by tape. Tape can interfere with proper seating.

• Hand-tighten first, then wrench-tighten slightly
  Over-tightening can crush washers and create leaks. Tighten until snug, then test under pressure and adjust if needed.

• Route hoses without sharp bends
  Tight bends can stress hoses and cause long-term failures.

After connections are made, keep the cabinet clear so you can inspect joints during testing.

Step 6: Turn Water On and Perform a Leak and Performance Check

Testing is the step that prevents callbacks and water damage.

1. Open angle stops slowly
   Turn on cold, then hot. Opening slowly reduces pressure shock.

2. Check all joints under the sink
   Look and feel around each connection with a dry paper towel. A paper towel shows moisture immediately.

3. Flush the faucet
   Run water for 1 to 2 minutes on both hot and cold. This clears debris that could clog the aerator.

4. Check handle operation and mixing
   Verify smooth control from cold to hot and confirm stable flow.

5. Inspect around the faucet base
   Splash a small amount of water around the base and confirm it does not seep under the faucet footprint.

If you see small leaks, tighten the connection slightly and re-test. Avoid large tightening jumps.

Choosing a Replacement Faucet That Fits Your Bathroom and Long-Term Needs

The faucet you select affects installation time and long-term user experience. A single lever basin mixer is often chosen because it delivers quick one-hand control and a cleaner deck layout.

Selection points that matter:

• Comfortable handle movement without hitting backsplash
• Stable body construction and finish durability for frequent wiping
• Reliable cartridge performance for smooth control
• Simple mounting hardware that stays rigid over years of use
• Finish coordination with other Bathroom Accessories

For renovations and multi-unit projects, consistent product geometry and repeatable installation results help reduce installer variability. Many project buyer teams prefer a faucet model that can be deployed across multiple rooms with predictable fit and a consistent look.

COIGN Single Lever Basin Mixer for Renovations and Projects

COIGN develops basin mixers with a focus on clean installation and stable daily operation. The product line supports modern bathroom styling while keeping practical service details in mind, including a solid mounting structure and finish options suited for humid environments. For wholesale and OEM supply programs, consistency across batches and clear configuration control are often as important as the design itself, especially when the same faucet is installed across many units. For more details, please view the products here: single lever basin mixer.

Conclusion

To replace a bathroom Sink Faucet, start by confirming sink hole compatibility and shutoff valve condition. Shut off water, remove the old faucet, clean the deck, then install the new faucet with careful alignment and even tightening. Connect supply lines correctly, open water slowly, and test every joint for leaks before final cleanup. With the right planning and a quality single lever basin mixer, the upgrade improves both daily control and the overall bathroom finish, while reducing the chance of future service issues.