You’ve found the faucet you want. Then you look under the sink and count holes — and the number doesn’t match. This is the single most common reason a kitchen faucet purchase goes wrong, and it’s solvable for a few dollars in either direction.
Faucet rocking on the deck? That is a separate fix — tightening a loose faucet base.
As an Amazon Associate I earn from qualifying purchases.
Count your holes first
Look at the back deck of the sink (or the countertop, if the faucet mounts there). Standard configurations:
- 1 hole — single-handle faucet, nothing else.
- 2 holes — faucet plus one accessory (sprayer, soap dispenser, or air gap).
- 3 holes — the most common: either a widespread faucet (handles separate from spout) or a single-handle faucet plus two accessories.
- 4 holes — faucet, sprayer, soap dispenser, and usually an air gap.
Also measure the spread — center to center between the outer holes. 8 inches is the standard widespread spacing, and 4 inches is centerset (more common on bathroom sinks). And check hole diameter: most accept a standard faucet shank, but an oversized hole needs a plate to cover it.
The measurement nobody tells you to take: deck thickness
Hole count and spread are the two everyone checks. Deck thickness is the one that stops the job at 8pm with the water off, and it is invisible until the faucet is in the hole.
Every faucet has a maximum mounting thickness — the depth of material its shank and hardware can clamp through. On a thin stainless sink deck nobody ever hits it. You hit it when the faucet mounts through a countertop instead: a stone slab, plus any plywood substrate, plus a deck plate and its gasket, adds up faster than you would think, and the mounting nut runs out of thread with the faucet still loose.
So before you buy:
- Work out what the faucet actually mounts through. Undermount sinks put the holes in the countertop; drop-in sinks put them in the sink deck. This is the fork in the road and people miss which side they are on.
- Measure the full stack, including anything you are adding under the base.
- Check the faucet’s stated maximum deck thickness before ordering, and if you are close, look for a model with a threaded shank rather than a short quick-mount stud — threaded shanks give you far more range.
The rule that solves 90% of cases
You can always cover extra holes. You cannot easily add one.
Adding a hole to a stainless sink needs a hole saw or a knockout punch and steady nerves. Adding one to granite, quartz, or cast iron means a diamond bit, water cooling, and real risk of cracking a countertop that costs more than the kitchen faucet. So when the counts don’t match, the cheap fix is almost always to cover, not to cut.
Too many holes: a deck plate or a hole cover
A deck plate (escutcheon) is a single plate that sits under the faucet base and spans the extra holes — the standard answer when you’re putting a single-hole faucet into a 3-hole sink. Many faucets ship with one; check the box before buying another.
- MAAYAYA 10″ deck plate for 8″ widespread, brushed nickel stainless — covers the standard 3-hole spread and secures with the faucet’s own hardware, with a foam gasket to seal against the deck.
If the hole you need to hide is away from the faucet — an old sprayer or soap dispenser opening off to one side — a deck plate won’t reach it. Use a snap-in cover instead:
- Plumb Pak PP21522 snap-in faucet hole cover, 1-1/2″ OD stainless — snaps into a standard sink hole, no tools.
Match the finish to the faucet, not the sink. A chrome plate under a brushed-nickel faucet reads as a mistake from across the room.
Do you actually need the air gap hole?
The fourth hole is usually there for a dishwasher air gap, and whether you need one is a live code question rather than a style choice — which is why it is worth checking before you cover it over permanently.
Under the plumbing code as adopted in Georgia, the waste connection of a residential dishwasher goes directly to a wye branch on the kitchen sink tailpiece, directly to the disposer’s dishwasher connection, or through an air break to a standpipe — and, in the same section, “the waste line of a residential dishwasher shall rise and be securely fastened to the underside of the sink rim or counter top.” That rise is the high loop, and under this code it is what is specified. A deck-mounted air gap fitting is not required by that section.
⚠️ Other jurisdictions do require a deck air gap, and inspectors differ. If your dishwasher currently drains through a deck fitting and you are planning to cover that hole, ask first — it is a five-minute call and it is much cheaper than drilling a granite counter later. Separately, the same chapter requires the dishwasher’s water supply to be protected by an air gap integral to the machine or by a backflow preventer, which is a different device entirely and lives inside the appliance.
Not enough holes
Fewer options, and all of them cost more:
- Pick a faucet that fits the holes you have. Cheapest and easiest — a single-hole pull-down puts the sprayer in the spout, so a 1-hole sink needs no accessories at all.
- Drill stainless with a proper hole saw or knockout punch. Doable, and the burr must be deburred so the gasket seals.
- Granite, quartz, or cast iron: get a pro. Diamond bit, wet cutting, and a real chance of cracking the slab. This is not the place to learn.
The order that makes install day short
Almost every miserable faucet swap is a sequencing problem, not a skill problem. The trick is that nearly everything is easier before the faucet is in the hole and you are lying on your back.
- Dry-fit the deck plate on the sink first, with the faucet resting in place, and look at it. Gaps, wrong finish, a plate that does not quite span the outer holes — find that now, not with the old faucet already in the bin.
- Assemble everything you can on the bench. Attach supply lines, sprayer hose and any quick-connects to the faucet body while it is on the counter in good light. Threads you can see are threads you do not cross.
- Water off, then open the faucet to drop the pressure before you disconnect anything.
- Old faucet out, then clean the deck properly. Scrape off old putty and silicone down to bare metal or stone. A new gasket sitting on a ridge of old sealant is the reason the new faucet rocks.
- Set the faucet, then tighten from underneath — and hold the spout square to the sink while somebody else pulls the nut up, or it will end up pointing at the drainboard.
- Connect, then turn the water on slowly with the faucet open, and let it run to clear debris before you fit the aerator.
While you’re under there
A faucet swap is the natural time to replace the parts you can only reach with the faucet out — supply lines and shutoff valves. Old multi-turn stops seize exactly when you need them, and old braided lines are the classic cause of an under-sink flood. See braided supply lines and under-sink shutoff valves. The nut up behind the basin is what a basin wrench exists for.
Two numbers worth knowing while you are down there. The code’s minimum supply pipe size for a kitchen sink is 1/2 inch, the same as for a dishwasher. And the maximum flow rate for a sink faucet is 2.0 gpm at 60 psi — so a listing advertising a notably higher flow is either quoting a different test condition or is not a fixture intended for this. The aerator is what sets that number, which is also why a faucet that feels weak is worth checking at the aerator before you blame the house.
If the faucet itself is fine and only the sprayer is failing, that’s a cheaper fix — see kitchen faucet sprayers. Shopping the faucet itself: best kitchen faucets.
FAQ
Can I use a 1-hole faucet in a 3-hole sink?
Yes — that’s exactly what a deck plate is for. It sits under the faucet base and covers the outer two holes. Many single-hole faucets include one.
What is standard kitchen faucet hole spacing?
8 inches center-to-center between the outer holes is the standard widespread spacing on kitchen sinks. 4-inch centerset is more common on bathroom sinks. Measure before ordering a deck plate.
Can I drill an extra hole in my sink?
In stainless, yes, with a hole saw or knockout punch. In granite, quartz, or cast iron, have a pro do it — it needs a diamond bit and wet cutting, and a cracked countertop costs far more than the faucet.
Can I cover the dishwasher air gap hole?
Check your local code before you do. Under the code as adopted in Georgia the dishwasher waste line is required to rise and be fastened to the underside of the sink rim or countertop — the high loop — and a deck-mounted air gap is not called for by that section. Other jurisdictions do require one, and inspectors vary. Ask first; it is far cheaper than drilling stone afterward.
Why won’t the mounting nut tighten on my new faucet?
Usually deck thickness. The faucet’s shank and hardware only clamp through so much material, and a stone countertop plus a substrate plus a deck plate can exceed it. Measure the whole stack and check the faucet’s maximum mounting thickness before ordering — models with a fully threaded shank give you much more range than short quick-mount studs.
Do the holes go through the sink or the countertop?
Depends on the sink. Drop-in sinks have the holes punched in their own deck; undermount sinks have nothing to punch, so the holes are drilled in the countertop. It changes what you measure, what you can cover, and what it would cost to add one.
Sources
- Georgia State Minimum Standard Plumbing Code 2018 (IPC 2018 with Georgia amendments), Chapter 4 — §409.4 Residential Dishwasher Waste Connection (wye branch on the sink tailpiece, the disposer’s dishwasher connection, or an air break to a standpipe; “the waste line of a residential dishwasher shall rise and be securely fastened to the underside of the sink rim or counter top”); §409.2 Water Connection (backflow protection by an integral air gap or a backflow preventer).
- Same code, Chapter 6 — Table 604.4, sink faucet maximum 2.0 gpm at 60 psi; Table 604.5, minimum fixture supply pipe size 1/2 inch for a kitchen sink and for a domestic dishwasher.
Related guides
Fix the 12 Most Common Plumbing Problems Yourself — Free Plumber’s Handbook — including the 10-minute faucet fixes anyone can do
Step-by-step fixes for the 12 most common problems — and exactly when to call a pro. Free and instant, from a licensed plumber. Save hundreds on calls you didn’t need.