Turning off the water supply under the sink is the essential first step, followed by disconnecting supply lines and mounting nuts to remove the old.
You twist the handle and a drip turns into a stream. Reaching under the sink, you spot rust on the old chrome and think about a new faucet. The immediate reaction is to call a plumber, but replacing a bathroom faucet is one of the most straightforward DIY projects for a weekend afternoon.
This walkthrough covers the full process from shut-off to leak test, with a focused look at the common mistakes that turn a quick job into a headache. You will need basic tools and about an hour of time.
Tools and Materials You’ll Need
Having the right tools on hand before you start prevents mid-project trips to the hardware store. A basin wrench is the most important specialty tool — it reaches the mounting nuts in the tight space under the sink where a standard wrench cannot fit.
Plumber’s tape (Teflon tape) is another must-have. It seals threaded connections and prevents leaks. You will also need an adjustable wrench, a screwdriver, a bucket or towel for residual water, and a flashlight to see the plumbing underneath. The new faucet should include mounting hardware, supply lines, and a drain assembly — check the box before starting.
Removing the Old Faucet — Why It’s a Critical Step
This part is where most DIY successes or failures begin. Rushing through removal can damage the sink, ruin the shut-off valves, or leave hidden debris that later causes problems. The goal is to get the old fixture out cleanly without creating extra work.
- Turn off the water supply: Locate the shut-off valves under the sink — typically one for hot and one for cold. Turn them clockwise until they stop. If they do not hold, turn off the main water valve for the house.
- Disconnect the supply lines: Use a wrench to loosen the nuts connecting the supply lines to the shut-off valves. Have a bucket ready to catch leftover water. Label the hot and cold lines if they are not color-coded.
- Remove the mounting nuts: From underneath, use a basin wrench to unscrew the nuts holding the faucet to the sink. For stubborn nuts, penetrating oil helps. If the faucet is old, the nuts may be corroded — patience prevents damage to the sink.
- Lift out the old faucet: Gently pull the faucet up from the top. Clear away any old plumber’s putty or silicone. Clean the sink surface so the new gasket seals properly.
- Remove the old drain assembly: Loosen the locknut under the sink holding the pop-up drain rod and lift the old drain body out. Set aside the old parts.
This removal sequence prepares the sink for the new faucet without unnecessary repairs to the shut-off valves or supply lines.
Installing the New Faucet
With the sink clean, insert the new faucet through the mounting holes. Match the faucet base to the sink configuration — center-set faucets work for standard three-hole sinks with 4-inch spacing, while widespread models need 6-inch or wider spacing. Secure the faucet from underneath with the included mounting hardware, tightening evenly.
Next, install the new drain body. Place the rubber washer and drain body through the sink hole, then secure it with the locknut from below. Attach the ball rod for the pop-up stopper according to the manufacturer instructions. Moen and other brands include detailed diagrams — refer to them. A step-by-step visual guide is also available in the replacing bathroom faucets guide from Home Depot.
| Faucet Type | Hole Configuration | Typical Spacing |
|---|---|---|
| Center-set | 3 holes | 4 inches (outer to outer) |
| Widespread | 3 holes | 6 to 16 inches |
| Single-hole | 1 hole | N/A (one large base) |
| Wall-mount | Mounts on wall | Varies |
| Vessel faucet | 1 or 3 holes | Matches vessel sink rim |
Choosing the right faucet for your sink’s hole pattern prevents returns and wasted effort. Measure the existing holes before buying.
Common Mistakes to Avoid
Even with good instructions, small oversights cause leaks or poor performance. The mistakes below come from plumbing pros who see the same errors repeatedly.
- Skipping plumber’s tape on threads: Without tape, water can seep through the tiny gaps in threaded connections. Wrap the tape clockwise two or three times around male threads before tightening.
- Overtightening connections: More force does not mean a better seal. Snug is enough; too much pressure can crack plastic fittings or strip brass threads. Hand-tighten plus a quarter turn with a wrench is the rule.
- Failing to flush supply lines before connecting: Old pipes accumulate sediment and debris. If you connect the new faucet without flushing, particles can clog the aerator or damage the cartridge. Run the water into a bucket for a few seconds before attaching the supply lines.
- Mixing incompatible materials: Brass fittings and galvanized steel corrode when joined, leading to leaks and joint failure. Use matching materials (brass to brass) or a dielectric union.
- Ignoring local building codes: Some jurisdictions require a licensed plumber for work involving shut-off valves or require permits for fixture replacement. Check before starting if you plan to sell the home.
Avoiding these five pitfalls keeps the installation simple and the faucet working smoothly for years.
Testing and Final Checks
Before you call the job done, test every connection. Turn the water supply valves back on slowly — first cold, then hot. Listen for hissing and look for drips under the sink. Run the faucet at full pressure for thirty seconds and check the drain for leaks. If you see moisture, tighten the connection slightly. The All About The House turn off water supply guide recommends starting with the supply off and turning it on only after all connections are tight.
Also test the pop-up stopper: raise and lower it several times to confirm smooth operation. If it sticks, adjust the pivot rod nut. A final wipe-down of the sink and faucet removes fingerprints and water spots.
| Check Point | Action |
|---|---|
| Water supply connections | Run water, inspect for drips |
| Drain body and locknut | Fill sink, release water, check under sink |
| Pop-up stopper | Operate lift rod; adjust if needed |
The Bottom Line
Replacing a bathroom faucet is a manageable weekend project when you plan ahead. The key steps are shutting off the water, removing the old fixture carefully, installing the new one with the correct hardware, and testing every joint for leaks. Using plumber’s tape, avoiding overtightening, and flushing the lines beforehand prevent the most common issues.
If the shut-off valves are stuck or the sink hole pattern does not match your new faucet, a licensed plumber can handle the mismatch quickly — better to call for help than to force a bad fit and risk water damage.
References & Sources
- Homedepot. “How to Replace a Bathroom Faucet” A bathroom faucet replacement involves removing the old fixture and installing a new one, typically including the faucet body, handles, drain assembly, and supply lines.
- All About The House. “Replacing a Bathroom Vanity Faucet and Drain” The first step in any faucet replacement is to turn off the water supply using the shut-off valves located under the sink.