Delta One Hole Bathroom Faucet: How to Choose and Install One (2026)

Updated November 2026

A Delta one hole bathroom faucet is a single-unit fixture that mounts through one opening in your vanity or sink deck. By the end of this guide, you will know how to confirm your sink has the right hole size, pick the right model for your style and water setup, and install the faucet yourself with basic hand tools. The process is manageable for most homeowners, but a few measurements and steps make the difference between a leak-free install and a callback.

What “One Hole” Means for Your Vanity

A one hole faucet uses a single mounting opening, typically 1-3/8 inches in diameter, for the faucet body, handle and spout together. Delta makes one-handle models that sit on that single hole, and some of them include a deck plate or escutcheon that covers small gaps around the base. Because everything runs through one point, you do not need the spacing that a centerset or widespread faucet requires. That makes one hole designs a good fit for compact vanities, powder rooms and older sinks that were drilled for a single-hole fixture.

Shopping for one? See our guide: Bathroom Sink Faucet One Hole: 7 Best Picks for Every Vanity (2026).

Before you shop, confirm what your sink already has. A one hole faucet will fit a sink with one pre-drilled hole, and it can also work on a sink with three holes if you use the included cover plate to hide the unused openings. It will not work on a sink with no pre-drilled hole unless you have the sink drilled by a professional, and drilling into some materials, such as quartz or glass, can crack the surface.

Step 1: Measure and Check Your Sink

Start by checking the number of holes in the sink deck and their spacing. If you have a single hole, measure its diameter. Most one hole bathroom faucets require a 1-3/8 inch hole, though some manufacturers specify a slightly different range, so compare the number in the product documentation to your measurement. Measure the thickness of your sink deck as well. Standard faucet mounting hardware typically accommodates decks up to about 2 inches thick, but thicker decks need longer shank hardware or a different mounting kit.

Next, check the clearance under the sink. Faucet bodies and supply lines need room, and the nut that tightens the mounting hardware needs access. Measure from the underside of the deck to the nearest obstruction, such as a drawer front or a cabinet brace. If you have less than a few inches, a right-angle basin wrench will help, and you should plan for a tight install.

Measurements to Write Down

• Sink hole diameter (inches)
• Number of pre-drilled holes and their centers, if more than one
• Sink deck thickness (inches)
• Vertical clearance under the deck (inches)
• Faucet height needed to clear the backsplash or mirror
• Spout reach from the center of the sink to the basin center

Step 2: Choose the Right Model

Once you know your sink, you can narrow the choice. Consider these factors:

• Spout height and reach. A taller spout clears deep bowls and gives room for hands and cups. A shorter spout suits compact vanities. Check the spout height and reach figures listed by the manufacturer against the depth of your basin.
• Handle style. Single-lever handles are the most common on one hole models. Some designs use a lever that moves up and down for flow and side to side for temperature.
• Finish. Chrome, brushed nickel and matte black are widely available. Choose a finish that matches your other fixtures so the set looks coordinated.
• Drain assembly. Confirm whether the faucet includes a pop-up drain or requires one separately. Mismatched drains are a frequent source of frustration.
• Water pressure and flow. Many Delta models are rated for a specific flow rate in gallons per minute. If your home has low water pressure, check the rating and consider a model with a flow regulator.

Owners often report that the drain and supply lines cause the most trouble when they are not sized correctly, so verify that the included parts match your sink before you buy.

Step 3: Gather Tools and Supplies

Most installs take one to two hours for someone comfortable with basic plumbing. Having everything ready prevents mid-job trips to the hardware store.

1. Adjustable wrench and basin wrench
2. Plumber’s putty or silicone sealant rated for sinks
3. Bucket and towels
4. Flashlight or headlamp
5. Supply line hoses, if not included
6. Pop-up drain assembly, if needed
7. Penetrating lubricant for stubborn nuts

Step 4: Install the Faucet

Shut Off the Water and Remove the Old Fixture

Turn off the shutoff valves under the sink, then open the faucet to drain remaining water. Disconnect the supply lines and remove the old faucet mounting nuts. If the old faucet is stuck, apply penetrating lubricant and wait ten minutes before trying again.

Prepare the Sink Surface

Clean the deck around the hole thoroughly. Remove old putty, caulk and grime. A clean, dry surface helps the base seal properly.

Set the Faucet and Gasket

Place the gasket or sealing ring on the faucet base as the manufacturer directs. Some models use plumber’s putty under the base. Insert the faucet through the hole and align the spout with the center of the basin before tightening anything.

Secure the Mounting Hardware

From below, slide the washer and mounting nut onto the threaded shank. Tighten evenly by hand first, then use the basin wrench to snug the nut. Avoid overtightening, which can crack ceramic or stone surfaces. Check that the faucet sits level and that the handle moves freely.

Connect the Drain and Supply Lines

Install the pop-up drain according to its instructions, connecting the drain body to the P-trap. Attach the supply lines to the shutoff valves, hand-tightening first and then using a wrench for a snug fit. Wrap threads with plumber’s tape where needed.

Test for Leaks

Turn the shutoff valves back on slowly. Run hot and cold water, check every connection for drips, and let the water run for a few minutes. Dry the connections with a towel and check again after an hour.

Common Mistakes and Tips

• Skipping the measurement step. Buying before you check hole diameter and deck thickness is the most common error.
• Overtightening the mounting nut. This can crack the sink or distort the faucet base.
• Ignoring the drain fit. A pop-up drain that does not match the faucet design will leak or fail to seal.
• Forgetting the gasket or putty. Without a seal, water will work its way under the base.
• Using the wrong cover plate. If your sink has extra holes, use the included escutcheon or a matching cover so the deck looks finished.

Keep the owner’s manual and part numbers on file. If a cartridge or valve later needs replacing, having the exact model number makes ordering much simpler.

Recommended gear

A basin wrench gives you reach under a tight vanity, which is often the hardest part of a faucet swap. View on Amazon

Silicone sink sealant helps seal the base and prevents water from migrating under the deck. View on Amazon

A headlamp keeps both hands free when you are working in the dim space beneath a vanity. View on Amazon

FAQ

Does a one hole faucet fit a three hole sink?

Yes, if you use the cover plate that comes with many models or buy one separately. The plate covers the two unused openings so the deck looks finished.

What hole size does a Delta one hole faucet need?

Most one hole bathroom faucets require a 1-3/8 inch hole, but check the specific model documentation to confirm the exact requirement.

Can I install it myself?

Many homeowners can complete the install with basic tools in one to two hours. If you are uncomfortable working with supply lines or the sink is damaged, consult a licensed plumber.

Do I need plumber’s putty?

Some models use a rubber gasket instead of putty. Follow the manufacturer’s instructions, since putty can interfere with certain designs.

Why is my new faucet dripping?

Check the mounting nut for looseness, confirm the gasket is seated, and inspect supply line connections. A drip at the spout often points to a cartridge issue rather than an install problem.

How do I know if my sink is thick enough?

Measure the deck thickness and compare it to the mounting hardware specification in the product documentation. Thicker decks may need extended hardware.

Will low water pressure affect my faucet?

Low pressure reduces flow but does not usually damage the faucet. Models with flow regulators can help you maintain a steady stream.

Conclusion

A Delta one hole bathroom faucet is a practical choice for compact vanities and single-hole sinks. Measure your deck and clearance carefully, match the drain and mounting hardware to your sink, and tighten connections without overdoing it. With the right preparation, most homeowners can finish the install in an afternoon.

Related reading

• Bathroom Faucet Three Hole: How to Choose and Install One (2026)
• 6 Best Bathroom Faucet One Hole Picks for Every Vanity (2026)
• Single Hole Faucet for Bathroom: 5 Best Picks Compared (2026)
• Price Pfister Bathroom Faucet Parts: Identify, Order and Replace the Right Ones
• Moen Bathroom Faucet One-Handle Review: Key Features Explained
• Delta Trinsic Bathroom Faucet Review: Key Features Explained

About the author