Single Handle Bathroom Faucet Installation Like a Pro (Delta and Moen)
By Julian Gill Updated · 6 min read
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In this article
Installing a single handle bathroom faucet is one of the best DIY plumbing projects for a homeowner. It needs a few basic tools, an hour or two and some patience under the sink. Here is how I install a Delta or Moen single handle faucet so it is tight, square and leak-free the first time.
Quick answer
To install a single handle bathroom faucet, shut off the water, remove the old faucet, set the new faucet on its gasket, tighten the mounting nut, install the drain, connect the hot and cold supply lines and test for leaks. Delta and Moen faucets install in nearly the same way.
Key takeaways
- Order matters: set up and check the drain stopper before you tighten everything.
- The gasket makes the seal: it sits between the faucet base and the sink.
- Hot on the left: connect the hot supply line to the left inlet and cold to the right.
- Flush before use: run the water without the aerator to clear debris.
Before You Start
Check the number of holes in your sink before you buy. Most single handle faucets need one hole. If your sink has three holes, choose a faucet that comes with a deck plate to cover the extra ones. Also check whether the faucet includes its own pop-up drain and supply lines.
Clear out the cabinet under the sink and lay down a towel. You will spend most of this job on your back, so a flashlight or headlamp helps a lot.
Tools and Materials You Need
- New single handle faucet (Delta, Moen or other brand)
- Adjustable wrench
- Pliers
- Basin wrench (helpful in tight spaces)
- Plumber's putty or silicone (for the drain, as the instructions say)
- Plumber's tape (PTFE)
- Braided supply lines, if not included
- Bucket, towels and a flashlight
Safety first
Turn off both shut-off valves under the sink, then open the old faucet to release the pressure. If the shut-off valves are old and do not close fully, turn off the main water supply instead. Keep a bucket under the connections to catch the water left in the lines.
Remove the Old Faucet
- Disconnect the supply lines
Loosen the nuts that join the supply lines to the shut-off valves and let the water drain into the bucket.
- Disconnect the drain linkage
Unscrew the pivot nut on the back of the drain pipe and release the lift rod from the clevis strap, if you are replacing the drain too.
- Remove the mounting nuts
Loosen the nuts that hold the faucet to the sink, using a basin wrench if you cannot reach them with pliers. Lift the old faucet out and clean the sink surface of old putty and grime.
How to Install a Single Handle Bathroom Faucet
Follow the steps in this order. Doing the drain before the final tightening saves you from taking things apart again later.
- Insert the gasket into the baseplate
Place the rubber gasket on the bottom of the faucet base or baseplate. It creates the watertight seal between the faucet and the sink, so make sure it sits flat.
- Set the faucet and attach the mounting nut
Feed the tailpieces or supply tubes through the hole in the sink. From below, slide on the washer and the mounting nut and tighten them by hand. Check that the faucet is straight, then snug the nut with a wrench.
- Install the drain
Fit the drain flange in the sink with plumber's putty or the gasket supplied, then tighten the drain body from below. Connect the lift rod and check that the stopper opens and closes properly. Do this before the final tightening, otherwise you will have to loosen everything to adjust it.
- Connect the supply lines
Attach the hot supply line to the hot shut-off valve (usually on the left) and the cold line to the cold valve. Tighten the fittings by hand, then a quarter turn more with a wrench. Do not over-tighten.
- Turn on the water and flush
Unscrew the aerator from the spout. Open the shut-off valves slowly, then run hot and cold water for a minute to flush out debris. Screw the aerator back on.
- Test for leaks
Run the faucet on hot, then cold, then mixed. Check every connection under the sink with a dry paper towel: the supply lines, the mounting nut and the drain. Fill the basin and let it drain to test the drain seal.
How Do You Install a Delta Single Handle Bathroom Faucet?
Moen and Delta faucets look different, but they install more or less the same way. Both use a gasket or baseplate on top, a mounting nut underneath and supply lines that connect to the shut-off valves. If you know how to install one, you know how to install the other.
The differences are in the details: the shape of the mounting hardware, whether the supply lines are attached, and the type of drain included. Each brand recommends its own parts, so use the drain and hardware that come in the box and follow its instructions where they differ from this guide.
Common Mistakes to Avoid
- Skipping the drain check: test the stopper before you tighten everything down.
- Over-tightening the fittings: it can crack plastic nuts or damage the washers. Hand tight plus a quarter turn is usually enough.
- Mixing up hot and cold: hot goes on the left. Check before you open the valves.
- Forgetting to flush: debris from the pipes can clog the aerator or damage the cartridge.
- Reusing worn supply lines: new braided lines are cheap insurance against a leak.
FAQs
How does a single-handle faucet work?
One handle controls both the hot and cold water. A cartridge inside mixes them: you move the handle one way for hot and the other way for cold, and lift or turn it to change the flow.
Why should I switch to a single-handle faucet?
You do not have to. Many people prefer one handle for its convenience and clean look, and it is a good choice when there is not enough room for a three-hole faucet. If you are switching, see our guide to converting a two-handle faucet to a single handle.
Can a single-handle faucet go on a sink with three holes?
Yes, if you use the deck plate (escutcheon) that many faucets include or offer as an option. It covers the two unused holes.
Do Delta and Moen faucets install the same way?
More or less. The parts look different, but the order is the same: gasket, faucet, mounting nut, drain, supply lines, then a leak test. Always follow the instructions in the box.
Do I need new supply lines with a new faucet?
Many faucets come with attached supply lines. If yours do not, or if the old ones are worn, buy new braided lines of the right length and connection size.
A single handle bathroom faucet is a very doable DIY job: gasket, faucet, mounting nut, drain, supply lines, flush and test, in that order. Delta and Moen both make good single handle faucets and both install the same way. If you are still choosing one, see our reviews of the best single handle bathroom faucets.