To tighten a kitchen sink faucet, turn off the water supply at the shut-off valves under the sink, access the mounting hardware beneath the sink deck, locate the mounting nut or mounting bracket that secures the faucet body to the sink, and tighten it clockwise using a basin wrench, adjustable wrench, or faucet installation tool until the faucet is firm and no longer moves. Most kitchen sink faucet tightening jobs take 15 to 30 minutes with basic tools and require no plumbing experience.
A loose kitchen sink faucet is one of the most common and most fixable plumbing maintenance issues in a residential kitchen. The faucet wobbles side to side, spins at its base, or rocks when the handle is operated, and the movement is often accompanied by a slow water leak at the faucet base because the loose mounting allows the deck gasket or plumber’s putty seal to separate. Left unaddressed, a loose faucet gradually enlarges the mounting hole in the sink deck, wears through the supply tube connections, and can eventually cause a water damage event under the sink. The fix is straightforward in nearly every case once the correct hardware is identified and the right tool is used to access it in the confined under-sink space.
Why Kitchen Sink Faucets Become Loose Over Time
Understanding why a kitchen sink faucet loosens provides insight into which specific component has failed and what the permanent fix requires versus a temporary tightening.
Mounting Nut Vibration Loosening
The most common cause of a loose kitchen sink faucet is a mounting nut that has vibrated loose over time. Every time the faucet handle is operated, a small rotational and lateral force is transmitted through the faucet body and down to the mounting hardware beneath the sink deck. Over thousands of handle operations across months and years, this repeated micro-vibration gradually backs the mounting nut counterclockwise off the faucet body threads, creating progressively more play in the faucet-to-sink connection. This process is identical to the reason threaded mechanical fasteners in machinery vibrate loose without a locking element.
Worn or Compressed Deck Gasket
Every kitchen sink faucet uses either a rubber deck gasket (also called a faucet base gasket, deck plate gasket, or escutcheon gasket) or a plumber’s putty seal between the faucet base plate and the sink deck surface to create both a water seal and a friction grip that helps prevent the faucet from spinning. Over time the rubber gasket compresses under the clamping force of the mounting nut, loses its elasticity, and thins to a point where the clamping preload is lost even though the mounting nut has not physically backed off. The faucet develops play even though the nut is technically still at its original torque position.
Water Damage to the Sink Deck Material
In sinks made from composite granite, acrylic, or those with a laminate countertop mounting hole surround, repeated moisture exposure around the faucet base causes the deck material to swell, soften, or delaminate. As the material compresses and deforms under the mounting hardware, the clamping action of the mounting nut loses its effectiveness even as the nut remains correctly tightened. This type of looseness is addressed by tightening the nut against the deformed material and checking that adequate contact surface remains.
Incorrect Original Installation
A faucet that has been loose since installation or that became loose very quickly after installation was likely not tightened adequately during the original installation. This is particularly common with DIY faucet installations where the under-sink space made it difficult to reach and properly torque the mounting nut. In tight installations such as deep apron-front sinks or farmhouse sinks with deep basins, the distance from the bottom of the sink deck to the mounting hardware below can exceed the reach of standard tools without a basin wrench.
Understanding Kitchen Sink Faucet Mounting Systems
Different faucet mounting systems require different tools and different tightening approaches. Identifying the specific system in your kitchen is the first step before selecting a tool.
Single-Hole Faucet with Threaded Shank and Mounting Nut
The most common kitchen faucet mounting configuration is a single-hole or three-hole faucet with a threaded shank (also called a tailpiece or mounting shank) that passes through the sink deck hole from above, with a plastic or metal mounting nut that threads onto the shank from below and clamps the faucet body down onto the deck surface.
The mounting nut in this system is almost always the component that has loosened. It is located directly under the sink deck, typically two to four inches below the sink basin floor, and must be tightened clockwise (when viewed from below, looking up toward the sink deck) to restore the clamping force. The nut is either plastic (more common in mid-range faucets) or brass or steel (more common in premium models). The plastic mounting nut used by manufacturers including Moen, Delta, Kohler, American Standard, Pfister, and Grohe in their mid-range lines is designed to be hand-tightened plus a specified wrench torque, and it is frequently the first component to loosen.
Deck Plate (Escutcheon) Faucet with Separate Mounting Bracket
Three-hole kitchen faucets that use a separate deck plate (also called an escutcheon plate) to cover multiple mounting holes use either the faucet body’s own mounting shank or a dedicated mounting bracket with mounting nuts for each hole. In this configuration, the deck plate itself may be loose (indicating the deck plate screws or nuts need tightening) while the faucet body is separately secured by its own mounting shank nut. Both can be loose simultaneously.
Widespread faucets (where the hot and cold handles are completely separate from the spout body) each have their own individual mounting shank and nut for the spout and each handle valve body. A widespread faucet that rotates may have only one of its three mounting nuts loose, or all three may need attention.
Mounting Nut with Plastic Wingnut (No-Tool Installation System)
Some lower-cost kitchen faucets use a plastic wingnut or thumbscrew mounting system that is designed to be tightened by hand during installation in tight under-sink spaces without any wrench. These systems are frequently the cause of loose faucets because the tightening force achievable by hand is significantly less than what a wrench provides, and the plastic material creeps over time under even moderate compressive load. If the faucet has a plastic wingnut that is already tight by hand, it must be replaced with a standard metal mounting nut on the same threads to achieve adequate clamping force for a permanent fix.
Top-Mount Deck Screws or Mounting Bolts
Some high-end kitchen faucets, particularly European and designer brands including Hansgrohe, Grohe, Rohl, and certain Kohler specialty models, use deck-mounted screws or mounting bolts that are accessible from above the sink deck rather than from below. These faucets typically have a base plate with screw holes visible at the top, and tightening them requires only a Philips or hex key screwdriver applied from above. This is the most DIY-friendly tightening configuration because no under-sink access is required.
Tools Required to Tighten a Kitchen Sink Faucet
The tool selection for tightening a kitchen sink faucet is entirely determined by the faucet mounting type and the depth of the sink basin. The key challenge in almost every under-sink tightening job is physical access, not mechanical complexity.
Basin Wrench
A basin wrench is the purpose-built tool for exactly this task and is the most important tool to own for any under-sink plumbing work. It consists of a long T-handle shaft with a pivoting jaw head at one end. The jaw clamps onto the mounting nut from below and the long shaft allows the user to reach and apply torque from a position outside the cabinet opening, without the arm being fully inside the confined space. The jaw is reversible for both tightening (clockwise) and loosening (counterclockwise) operations.
Standard basin wrench models appropriate for kitchen faucet tightening include the Ridgid 2014 Basin Wrench, the Ridgid 40697 Faucet and Sink Installer, the Husky 10-in. Basin Wrench, and the General Wire Spring BW-12 Basin Wrench. The working length of the shaft should be at minimum 10 inches for standard-depth sinks and 12 to 16 inches for deep farmhouse or apron sinks.
Adjustable Wrench
For mounting nuts that are accessible by direct reach without needing the extended reach of a basin wrench (typically in shallow sinks or in kitchen renovations where the countertop has been removed), a standard adjustable wrench in the 8-inch to 10-inch size range provides adequate jaw opening for most plastic mounting nuts (which are typically 1 to 1.5 inches across their flats) and metal mounting nuts.
Faucet Nut Wrench (Plastic Nut Wrench)
A plastic nut wrench or faucet installation wrench such as the Danco Plastic Nut Wrench, Plumb Pak Faucet Nut Wrench, or LASCO Faucet Nut Wrench is designed specifically for the large-diameter plastic mounting nuts that most Moen, Delta, and Kohler faucets use. These wrenches have a star-shaped or multi-point profile that engages the castellations or flat faces of the large plastic nut, providing grip that a standard wrench jaw (which is too small or the wrong shape for many plastic nuts) cannot achieve.
Faucet Installation Tool (Multi-Function)
The Ridgid 40697 Faucet and Sink Installer and similar multi-function faucet installation tools combine the reach of a basin wrench with a driver bit adapter and are compatible with both the large plastic nuts on modern faucets and the smaller hex-drive nuts found on some models. The Milwaukee 49-16-2700 Basin Wrench is another well-regarded multi-function option that includes multiple adapter attachments.
Allen Wrench (Hex Key Set)
For set screws that secure the faucet handle to the faucet body (preventing the handle from spinning rather than addressing the whole faucet body movement), a set of metric and SAE Allen wrenches (hex keys) is required. Most kitchen faucet handle set screws use 3/32-inch, 1/8-inch, or 3/16-inch (SAE) or 2 mm, 2.5 mm, or 3 mm (metric) hex keys. A ball-end hex key set such as those from Bondhus, Wiha, or PB Swiss Tools allows driving at an angle, which is useful in tight handle cap spaces.
Headlamp or Flashlight
A headlamp worn on the forehead is the most practical lighting solution for working under a kitchen sink because it leaves both hands free. A headlamp keeps the light source directed at whatever the eyes are focused on, which is critical for locating the specific mounting nut and confirming wrench engagement in a dark, cluttered under-sink cabinet. Black Diamond Spot 400 and Petzl Tactikka Plus are highly regarded options for plumbing work.
Step-by-Step Guide to Tighten a Kitchen Sink Faucet
Step 1: Turn Off the Water Supply and Clear the Cabinet
Turn off the hot and cold shut-off valves under the sink fully clockwise. While tightening a faucet does not require the water to be off as a strict plumbing necessity (since no fittings are being disconnected), closing the valves prevents accidental handle operation from sending water through the system while tools are positioned under the sink. Remove all items from the under-sink cabinet to create maximum access and workspace. Place a headlamp or flashlight to illuminate the underside of the sink deck clearly.
Step 2: Identify the Mounting Hardware Configuration
Look up at the underside of the sink deck from the cabinet interior. Identify the faucet’s mounting shank or shanks passing through the deck holes from above. Locate the mounting nut threaded onto the shank immediately below the deck surface. Determine whether the nut is plastic (cream, white, or light gray colored, typically larger diameter with castellations or flats) or metal (brass or chrome, smaller diameter with standard hex flats). Note the approximate diameter of the nut to select the correct tool.
Also examine whether the faucet has a mounting bracket or mounting plate with separate retaining nuts, whether there are deck screws visible from above that may also need attention, and whether the supply tubes are attached directly to the mounting shank or run separately.
Step 3: Inspect the Deck Gasket
Before tightening, push firmly down on the faucet base plate from above to check whether the faucet compresses slightly, which indicates the deck gasket is compressed and deformed. If the faucet is loose and wobbles but also has a water leak at the base, the deck gasket may need to be replaced during this service rather than simply tightened. A replacement gasket matched to the faucet brand and model is available from the manufacturer or from plumbing supply stores.
If the gasket is still in adequate condition, proceed to tightening. If the gasket is visibly cracked, deformed, or hardened, plan to replace it during this job by disconnecting the supply tubes, removing the faucet, replacing the gasket, and reinstalling.
Step 4: Position the Basin Wrench on the Mounting Nut
Position the basin wrench jaw around the mounting nut from below. Confirm the pivot jaw is oriented for clockwise (tightening) rotation by checking that pulling the handle counterclockwise (from the user’s perspective below) advances the jaw in the tightening direction on the nut. Most basin wrenches have a pivoting jaw that is flipped to reverse direction; confirm the orientation before applying force to avoid loosening the nut further.
Engage the jaw on the nut flats or castellations with full engagement, not just the edge of the nut. Partial jaw engagement causes the tool to slip under torque, rounds the nut faces, and reduces tightening effectiveness.
Step 5: Tighten the Mounting Nut to the Correct Torque
Apply firm, steady clockwise torque to the mounting nut using the basin wrench. For a plastic mounting nut, the correct torque is achieved when the faucet base plate is firmly compressed against the sink deck and the faucet no longer moves in any direction when pushed from above. This typically corresponds to hand-tight plus two to three full turns of the wrench. Do not overtighten plastic mounting nuts; applying excessive torque with a wrench cracks the nut or strips the threads on the plastic shank. If using a metal mounting nut, standard wrench torque to snug is appropriate, typically 15 to 25 foot-pounds in the context of faucet mounting.
Test the faucet from above after each wrench turn by attempting to rotate or rock it. Stop tightening as soon as no movement is detectable.
Step 6: Check and Tighten the Deck Plate Screws (If Applicable)
If the faucet has a separate deck plate (escutcheon) covering multiple holes, inspect whether the deck plate itself is loose independently of the faucet body. Deck plates are typically secured by their own screws or nuts accessible from below in a separate position from the main mounting nut. Tighten these separately using a Philips screwdriver or a small wrench as appropriate.
For faucets with top-mount deck screws accessible from above (typically covered by decorative caps that pry off with a plastic tool), tighten these screws in a star pattern if there are multiple screws to ensure even clamping force distribution across the deck plate.
Step 7: Tighten the Handle Set Screw (If the Handle Is Spinning)
If the kitchen faucet body is now secure but the handle itself spins on the faucet cartridge stem, the problem is a loose handle set screw rather than a loose mounting nut. Locate the decorative cap on the top or side of the handle and pry it off with a small flat-head screwdriver or the point of a utility knife. Beneath the cap is a set screw in either Philips, flathead, or hex (Allen) configuration. Tighten this screw clockwise until snug. Replace the decorative cap.
For single-handle faucets, the set screw is typically located under the handle cap directly on top. For two-handle faucets, each handle has its own set screw under its own cap.
Step 8: Restore Water Supply and Test
Turn the shut-off valves back on fully counterclockwise. Operate both the hot and cold handles through their full range of motion while watching the faucet base from above for any movement. Apply lateral force to the faucet handle and body to confirm the tightened mounting has eliminated all play. Check under the sink for any seeping at the supply tube connections or the mounting area that might indicate the nut was overtightened against a compromised gasket. If the faucet is firm and dry with no movement, the job is complete.
Benefits of Tightening a Kitchen Sink Faucet Promptly
A loose kitchen sink faucet is not simply an annoyance. Addressing it promptly produces several concrete practical benefits that justify the 15 to 30 minutes of repair time.
A loose faucet that is allowed to move repeatedly during daily use enlarges the mounting hole in the sink deck progressively. In stainless steel sinks, this enlargement is slow because the metal resists abrasion, but in composite granite sinks, acrylic sinks, and laminate countertops, the mounting hole diameter increases measurably over months of movement, eventually reaching a point where standard mounting hardware can no longer securely bridge the oversized hole. At that stage, a backing plate or specialized oversized mounting hardware is needed, significantly complicating what was a simple nut tightening.
A loose faucet also stresses the supply tube connections at the faucet inlets with every movement, particularly the compression fittings or push-fit connections at the top of the supply tubes. Repeated micro-movement at these connections gradually works them loose, producing a slow drip under the sink that goes undetected in the enclosed cabinet and creates the moisture conditions for mold growth.
Tightening the faucet also protects the faucet cartridge or ceramic disc valve inside the body from lateral stress. Faucet cartridges are designed to handle vertical compressive forces from normal handle operation, but lateral loading from a wobbling faucet body can crack ceramic disc wafers, deform rubber seals, and cause premature valve failure that would otherwise not occur for many years.
Comparison Table: Kitchen Sink Faucet Mounting Types and Best Tools
| Mounting Type | Mounting Hardware | Best Tool | Access Required | Difficulty | Common Brands |
|---|---|---|---|---|---|
| Single-hole with plastic mounting nut | Large plastic nut | Plastic nut wrench or faucet installation tool | Under-sink | Easy | Moen, Delta, Kohler, American Standard |
| Single-hole with metal mounting nut | Brass or steel hex nut | Basin wrench or adjustable wrench | Under-sink | Easy | Pfister, Grohe, Hansgrohe |
| Deck plate faucet with bracket and bolts | Mounting bracket nuts | Basin wrench | Under-sink | Easy to Moderate | Delta, Moen, American Standard |
| Widespread faucet (3 separate shanks) | Three individual mounting nuts | Basin wrench (each separately) | Under-sink | Moderate | Kohler, Grohe, Hansgrohe, Rohl |
| Top-mount deck screws | Deck screws under decorative caps | Philips or hex screwdriver from above | Above sink | Very Easy | Rohl, some Kohler and Grohe models |
| Plastic wingnut (DIY installation system) | Plastic wingnut | Hand tighten, then upgrade to metal nut | Under-sink | Easy (upgrade needed) | Lower-cost builder-grade faucets |
| Handle set screw (handle spinning only) | Allen or Philips set screw | Allen wrench or Philips screwdriver | Handle cap | Very Easy | All brands |
| Deep-basin farmhouse / apron sink | Any of above but deeper reach | Extended basin wrench 12 to 16 inch | Under-sink with extension | Moderate | Kohler, Rohl, Kraus |
Common Mistakes When Tightening a Kitchen Sink Faucet
Overtightening the Plastic Mounting Nut
The single most common mistake when tightening a kitchen sink faucet is applying too much torque to the plastic mounting nut using a wrench. The plastic material used in the mounting nuts of most mid-range kitchen faucets from Moen, Delta, and American Standard is engineered to a specific torque limit. Exceeding this limit splits the nut radially, strips the internal threads, or cracks the plastic faucet shank that the nut threads onto. A cracked shank requires complete faucet replacement. The correct stopping point for a plastic mounting nut is the first moment of firm resistance after the nut contacts the mounting hardware, which is normally snug by hand plus two to three careful wrench turns rather than maximum wrench effort.
Tightening Without Checking the Deck Gasket First
Tightening the mounting nut against a cracked, hardened, or heavily compressed deck gasket reapplies clamping force through a compromised seal. The faucet may feel temporarily firm but will loosen again within weeks because the degraded gasket cannot hold the mounting preload. Every faucet tightening job should include a visual and tactile inspection of the deck gasket condition before tightening. If the gasket is visibly deteriorated, replace it as part of the same service.
Attempting the Job Without a Basin Wrench
Using an adjustable wrench, a pair of pliers, or a standard socket wrench to reach and tighten a mounting nut that is deep beneath the sink deck almost always results in scraped knuckles, insufficient torque, and incomplete tightening because these tools do not have the reach geometry required for under-sink work. A basin wrench costing $15 to $35 at any hardware store is the correct tool for this job and makes the difference between completing the task in 10 minutes and struggling for an hour with the wrong tools. The Ridgid and Husky models available at hardware retailers such as Home Depot and Lowe’s are fully adequate for residential kitchen faucet tightening.
Not Identifying Whether the Faucet Body or the Handle Is Loose
Many homeowners attempt to tighten the mounting nut when the faucet base is already firm and the actual loose component is the handle set screw or the handle adapter. A handle that spins freely without the whole faucet body moving requires only a set screw tightening rather than under-sink work. Confirming which component is loose before starting prevents unnecessary under-sink access when the fix requires only a screwdriver applied to a set screw accessible from the top of the handle.
Ignoring the Associated Water Leak at the Faucet Base
A loose faucet almost always produces a water seeping leak at the faucet base because the movement breaks the seal between the deck gasket (or putty seal) and the sink deck surface. Tightening the mounting nut restores the mechanical stability but does not necessarily restore the water seal if the gasket has been damaged by the movement. Always run the faucet for several minutes after tightening and inspect the faucet base from above for any water weeping from under the base plate. If seeping continues after tightening, the gasket requires replacement and the faucet must be removed and reinstalled with a fresh seal.
Frequently Asked Questions
How do I tighten a kitchen sink faucet that keeps coming loose repeatedly?
If your kitchen sink faucet keeps coming loose after tightening, the underlying cause is either a worn deck gasket that can no longer hold the mounting preload, a plastic mounting nut that has cracked or had its threads stripped so it can no longer develop clamping force, or the mounting hole in the sink deck has become enlarged from repeated movement and no longer provides a firm surface for the mounting hardware to clamp against. To fix a kitchen sink faucet that repeatedly loosens, remove the faucet completely, replace the deck gasket with a new one matched to the faucet model, replace the plastic mounting nut with a new one from the manufacturer or a compatible universal replacement, and reinstall with correct torque. If the mounting hole is enlarged in a composite or laminate sink deck, a deck plate backing plate or faucet stabilizer bar can be used to distribute the clamping load over a wider area.
What tool do I need to tighten a kitchen sink faucet under the sink?
The primary tool for tightening a kitchen sink faucet from below is a basin wrench, which has a long shaft with a pivoting jaw that can reach and grip the mounting nut beneath the sink deck from a position outside the cabinet. For faucets with large plastic mounting nuts, a plastic nut wrench or faucet installation tool such as the Danco Plastic Nut Wrench or the Ridgid 40697 Faucet and Sink Installer provides the correct jaw profile for the nut’s castellations. For faucets with top-mount deck screws accessible from above the sink, only a Philips screwdriver or hex key is needed. A headlamp is equally important as the wrench for working in the dark under-sink space.
Can I tighten a kitchen sink faucet without turning off the water?
Technically yes, tightening a kitchen sink faucet does not require shutting off the water supply because the tightening process involves only the mounting hardware beneath the sink deck and does not disconnect any supply line fittings. However, turning off the hot and cold shut-off valves under the sink is strongly recommended because any accidental handle operation during the work sends water through the system, and tools or body position near the supply tube connections can inadvertently loosen a fitting if the lines are pressurized. Closing the shut-off valves takes 30 seconds and eliminates any risk of an accidental water release under the sink during the tightening process.
How do I tighten a kitchen sink faucet on a deep farmhouse or apron sink?
Tightening a kitchen sink faucet on a deep farmhouse sink or apron-front sink requires a long-reach basin wrench with a shaft length of at least 12 to 16 inches to bridge the greater distance from the cabinet access point to the mounting nut beneath the deep sink deck. Standard 10-inch basin wrenches may not reach. Products such as the Ridgid 2019 Extended Reach Basin Wrench or the Husky 16-in. Basin Wrench are designed for deep-sink applications. A right-angle ratchet adapter with a socket can also be used in some configurations to reach mounting hardware from the side. Position a small step stool or cushion on the kitchen floor to allow comfortable positioning while reaching into the deep cabinet from below.
Why is my kitchen sink faucet handle loose but the base of the faucet is firm?
If the base of the kitchen sink faucet is firm against the sink deck but the handle is loose or spinning, the problem is a loose handle set screw inside the handle body rather than a mounting nut problem. The set screw is typically accessible under a decorative cap on the top or side of the handle that pops off with a small flat-head screwdriver or utility knife. Under the cap, a small Allen (hex) set screw or Philips screw secures the handle to the faucet cartridge stem. Tightening this screw clockwise with the appropriate Allen wrench or screwdriver resolves the loose handle without any under-sink work. Most kitchen faucets from Moen, Delta, Kohler, and Pfister use a 3/32-inch or 1/8-inch Allen set screw for this purpose.
How tight should a kitchen sink faucet mounting nut be?
A kitchen sink faucet mounting nut should be tightened to the point where the faucet base plate is firmly compressed against the sink deck and the faucet does not move in any direction when pushed or twisted firmly by hand. For a plastic mounting nut, this is typically hand-tight plus two to three complete wrench turns, after which point the nut is snug and any additional torque risks cracking the nut or the faucet shank. For a metal mounting nut (brass or steel), the appropriate final torque is firm wrench-tight without straining the tool, typically equivalent to 15 to 25 foot-pounds. No specific calibrated torque value is required for a kitchen sink faucet mounting nut; the practical test is that the faucet does not move when pushed from above.
How much does a plumber charge to tighten a kitchen sink faucet?
A licensed plumber typically charges $75 to $150 for labor to tighten a kitchen sink faucet, with the job taking 20 to 40 minutes of on-site time. If the deck gasket requires replacement during the same service call, add $10 to $30 for the gasket part. If a basin wrench or specialized tool is needed and the homeowner does not already own one, purchasing the tool for a DIY repair costs $15 to $35, which is significantly less than the plumber’s labor rate. Tightening a kitchen sink faucet is one of the most straightforward and cost-effective DIY plumbing maintenance tasks available to a homeowner with basic tool literacy.
Can a loose kitchen sink faucet cause water damage under the sink?
Yes, a loose kitchen sink faucet can directly cause water damage under the sink through two mechanisms. First, the movement of the loose faucet body breaks the seal between the deck gasket and the sink deck surface, allowing water from normal faucet use to seep through the gap between the faucet base plate and the sink, dripping into the cabinet interior. This slow drip goes undetected in the enclosed cabinet and creates the moisture conditions for mold growth on the particleboard cabinet base and back panel. Second, the repeated movement of a loose faucet body stresses the supply tube fittings at the faucet inlets with each handle operation, gradually loosening the compression fittings or swivel nuts at the top of the supply tubes and producing a separate drip at those connections. Both of these water damage pathways develop slowly and silently, which is why addressing a loose kitchen sink faucet promptly is important for preventing cabinet mold and sub-floor water damage.
Conclusion
Tightening a kitchen sink faucet is one of the most accessible DIY plumbing maintenance tasks in the home, requiring a $15 to $35 basin wrench, a headlamp, and 15 to 30 minutes of work.
The key to a permanent fix rather than a temporary one is identifying whether the loose component is the mounting nut beneath the sink deck, the deck plate screws, or the handle set screw, and choosing the correct tool and torque for the specific hardware involved.
Inspecting the deck gasket condition before tightening and replacing it if it is compressed or cracked prevents the faucet from loosening again within weeks.
Addressing the problem promptly protects the sink deck from hole enlargement, the supply tubes from connection fatigue, and the under-sink cabinet from the moisture damage that a seeping faucet base leak produces silently over months.