A bathroom faucet replacement is similar to a kitchen faucet swap with one significant difference: bathroom sinks have lower mounting clearance, making the under-sink work physically tight. Drain assembly typically comes off too, since most faucet replacements include a new drain. The job is genuinely 1-2 hours including drain plumbing.
This guide covers single-handle and widespread (two-handle) bathroom faucets. Vessel sink faucets and wall-mounted faucets use different installations covered separately.
Before you start
Three things to settle:
1. Single-hole, centerset, or widespread. Single-hole: 1 hole in sink, single-handle faucet. Centerset: 4-inch on-centre 3-hole configuration with cover plate (most common in older Canadian bathrooms). Widespread: 8-inch or 16-inch on-centre 3-hole with separate hot/cold handles. Match the new faucet to your existing sink hole configuration.
2. Drain replacement included?. Most bathroom faucets ship with a matching drain assembly. The new drain replaces the existing pop-up or grid drain. Replacing the drain at the same time as the faucet is the standard approach since the parts match in finish.
3. Pop-up vs grid drain. Pop-up: drain has an internal stopper that lifts/closes via a lever behind the faucet. Most common in modern bathrooms. Grid drain: open mesh drain, no stopper. Used in vessel-sink installations and some commercial designs. Match new drain type to faucet type — pop-up faucets need pop-up drains.
What you'll need
Tools
- Adjustable wrench
- Basin wrench (essential)
- Slip-joint pliers
- Bucket and old towels
- Flashlight
- Plumber's tape
- Phillips screwdriver
Materials
- New bathroom faucet (matching sink hole configuration)
- Replacement drain assembly (often included)
- Plumber's putty (for drain seal)
- Replacement supply lines if existing are old
Replace the drain at the same time
Most bathroom faucet kits include a matching drain. Replacing the drain at the same time means the metal finishes match (chrome, brushed nickel, etc.). Mixing finishes between faucet and drain looks unfinished.
It also catches old drain issues — corroded fittings, clogged pop-up assemblies — before they fail later.
Step-by-step instructions
Shut off water and drain residual
Close the shut-off valves under the sink (turn clockwise).
Open the faucet to relieve pressure. Place a bucket under the supply line connections and disconnect supply lines from the faucet.
Disconnect the existing drain
Below the sink, disconnect the P-trap (the U-shaped pipe). Loosen the slip-joint nuts on each end with slip-joint pliers, drop the trap, drain residual water into the bucket.
Disconnect the pop-up linkage if present. The lever behind the faucet connects to a horizontal rod that runs into the drain assembly.
Remove the existing faucet
Below the sink, use a basin wrench to loosen the faucet's mounting nuts (counterclockwise). Remove washers.
Lift the old faucet up out of the sink.
Remove the existing drain
The drain has a body extending below the sink with a large nut and gasket. Loosen the nut with slip-joint pliers, drop the drain body, lift the drain flange out from the top of the sink.
Clean the sink mounting area
Remove old plumber's putty, mineral deposits, and grime. The new faucet and drain must seat against clean surfaces.
Wipe down with a non-abrasive cleaner.
Install the new drain
Roll a rope of plumber's putty (1/4-inch diameter) around the underside of the drain flange. Set the flange into the sink's drain hole.
Below the sink, install the drain's body components per the manufacturer's instructions. Tighten the locking nut from below — hand-tight plus a quarter turn.
Connect the pop-up linkage (the horizontal rod through the drain body).
Install the new faucet
Lower the new faucet into the sink mounting holes. Hold from above while installing mounting hardware below.
Tighten mounting nuts with the basin wrench — hand-tight plus a quarter turn. Don't over-tighten.
Connect supply lines
Attach hot supply line to hot shut-off valve, cold to cold. Apply Teflon tape on threads if compression fittings.
Hand-tighten supply line nuts, then snug a quarter to half turn with a wrench.
Reconnect the P-trap
Reattach the P-trap to the new drain assembly's tail piece and the wall drain pipe.
Tighten slip-joint nuts hand-tight plus a quarter turn — these are slip-joint connections that don't need much torque.
Restore water and test
Open shut-off valves. Watch for leaks at supply line connections.
Open faucet, run hot and cold. Verify no leaks at the faucet base, the drain seal, or under the sink at the trap.
Test the pop-up: lift and lower the lever, watch the stopper rise and fall in the drain.
Common mistakes that cost you
- Mixed finishes between faucet and drain. Match faucet and drain finishes for a coordinated look.
- Skipping plumber's putty. Drain leaks under the sink immediately. Always seal.
- Over-tightening. Bathroom mounting hardware is smaller and crackes more easily than kitchen. Hand-tight plus quarter turn only.
- Pop-up linkage misaligned. Lever doesn't move stopper. Adjust the pivot rod and clip until smooth operation.
- Wrong faucet for sink hole configuration. Single-hole faucet on a 3-hole sink without cover plate is awkward. Plan based on existing holes.
Frequently asked questions
How do I know my faucet hole spacing?
Measure between the centres of the outer holes on your sink. Single hole: 1 hole. 4-inch centerset: 4 inches between outer holes (typical older bathrooms). 8-inch widespread: 8 inches (modern wider designs).
Many faucets adjust between centerset and single-hole with included covers. Verify before buying.
Why does my drain leak after replacement?
Most common: insufficient plumber's putty under the drain flange or the drain body's gasket isn't seated correctly.
Drop the trap, remove the drain, re-install with fresh putty and ensure the gasket is properly positioned.
Can I install a vessel sink faucet on a regular sink?
Vessel sink faucets are taller (designed for above-counter sinks). On a standard sink, they may be too tall and the spout overshoots the bowl.
Match faucet height to sink type. Standard sinks: 4-8 inch faucets. Vessel sinks: 12+ inch faucets.
When to call us instead
If your bathroom plumbing has corrosion, leaks, or doesn't meet modern standards, replacing fixtures is a small part of a larger plumbing update. We do bathroom renovations including plumbing as fixed-price work.
Book a free 60-minute site visit →Related Ottawa services
If you're refreshing the bathroom, our bathroom renovation team handles plumbing, fixtures, and tile as fixed-price scopes. Book a free 60-minute consultation.