Faucet Repair Guide ·16 min read

Faucet Replacement Parts: The Homeowner’s Glossary [2026]

By Thomas Kwayne · September 11, 2026 · Fact-checked against manufacturer documentation and authoritative trade sources.

Faucet replacement parts are the second-most-expensive mistake in DIY faucet work, right behind misidentifying the faucet brand itself. Buy the wrong cartridge and your $25 fix doesn’t fix anything. Stock the wrong O-ring kit and you’re back at the hardware store on a Saturday morning. Worse, most homeowners don’t even know which parts are likely to fail — so they end up overbuying or, more commonly, having nothing on hand when a drip starts at 9pm on a Sunday.

This guide is the homeowner’s glossary of faucet replacement parts. What each part actually does, how long it typically lasts, whether it’s universal or brand-specific, what it costs, and which faucet replacement parts you should keep in a drawer “just in case.” If you’ve already identified your faucet brand and model — and if you haven’t, start with the brand identification guide — this is where you figure out what to buy and what to stockpile.

Faucet Replacement Parts: The Quick Stock List

For homeowners who want the five-minute version, here’s the consensus “keep-on-hand” list of faucet replacement parts. Total cost: roughly $20–$30. Saves you one emergency Home Depot run, every time.

Assorted O-rings and rubber washers — $5–$10 for a multi-size bag. Worn seals are the single most common cause of faucet drips.
Spare aerators (one kitchen, one bath) — $3–$6 each. Clogged aerators cause low flow; replacement is a five-minute fix.
Faucet repair/rebuild kit matched to your brand — $5–$15 for generic; $20–$30 for Moen or Delta OEM. Includes seals, springs, and seats.
One spare braided stainless supply hose — about $10. Stops a sudden under-sink leak cold.
Plumber’s tape and silicone sealant or plumber’s putty — $3–$8. Not parts, but you’ll need them whenever you reassemble anything.

Keep these faucet replacement parts in a labeled drawer with the rest of your plumbing tools. When a leak starts on a holiday weekend, you’ll know exactly where to look.

Cartridges and Valve Stems — The Brain of the Faucet

The cartridge (sometimes called the valve stem or valve cartridge) is the most expensive of the faucet replacement parts most homeowners ever buy — and the most common single point of failure in single-handle faucets. It controls hot/cold mix and on/off flow. Pull it out and water stops; install a worn-out one and you get drips, stiff handle feel, or uneven temperature.

Cartridges are almost always brand-specific. A Moen 1225 won’t fit a Delta faucet. A Kohler ceramic cartridge isn’t interchangeable with Moen’s. Some “universal” cartridges exist within a brand family (Delta’s RP19804, for instance, covers Monitor 1300/1400 Series tub and shower valves made before March 2006 – one part number across a family, but only that family), but cross-brand universality is a myth — and buying based on visual similarity is how homeowners end up returning parts.

Common cartridge part numbers worth knowing:

Delta: RP25513 and RP47422 for two-handle sink faucets. (RP46074 and RP19804 are listed here because homeowners search them constantly, but Delta lists both as tub/shower valve cartridges – MultiChoice 13/14 Series and Monitor 1300/1400 respectively – not sink-faucet parts.)
Moen: 1200, 1222 (PosiTemp shower), 1225 (the most common single-handle kitchen/bath cartridge in faucets made before about 2009)
Kohler: various ceramic-disc models – Kohler sells sink-faucet parts by faucet model rather than by a small set of universal numbers, so identify the model first. (Two Kohler numbers homeowners search that are not sink-faucet cartridges: GP500520 is Kohler’s “Cartridge For Pressure Balancing Unit (Shower)”, and GP30420 is not a cartridge at all – Kohler lists it as an “o-ring and bearing seal kit”. Check the part type before you order.)
Pfister: 974-291 series, 910-031

Cartridges run $15–$50 retail for OEM at Home Depot, Lowe’s, or directly from the manufacturer. Aftermarket or generic versions run $10–$25 but quality varies; brand-name is worth the extra five dollars for a part that lasts ten years. If your faucet is leaking from the spout when fully shut off, the cartridge is the most likely culprit — see Why Is My Faucet Leaking? for the full diagnostic flow before you order.

Aerators — The Tip That Saves Your Water Bill

The aerator is one of the most overlooked faucet replacement parts — a screw-on screen at the very end of the faucet spout. It mixes air into the water stream to reduce splashing, soften the flow, and cut water use without cutting perceived pressure. Most kitchen aerators flow 1.5–2.2 gallons per minute (GPM); bathroom aerators are held to less than that – EPA WaterSense labeling requires a maximum of 1.5 GPM for bathroom sink faucets, against a 2.2 GPM standard flow.

Aerators clog. That’s the failure mode 90% of the time — not a worn-out part, just mineral scale and sediment building up in the mesh. When your kitchen faucet starts spitting or flow drops noticeably, the aerator is almost always the first place to check. Unscrew it (often by hand, sometimes with pliers wrapped in tape), soak it in white vinegar overnight, scrub the mesh, and reinstall. If that doesn’t restore flow, replace it — they’re cheap.

These faucet replacement parts are mostly universal. Standard thread sizes are 15/16″ male (most common) or 55/64″ female. Adapters cover almost any non-standard thread. Replacements run $3–$10 each at any hardware store, and Home Depot, Lowe’s, and Ace all carry generic packs. Brand-specific aerators exist (Delta and Moen sell them under their own SKUs) but a $4 generic with the right thread works equally well for most kitchens and bathrooms.

One catch: some modern pull-down kitchen faucets use a proprietary cache aerator integrated into the spout head, not a separate screw-on. If you can’t see threads at the tip, check the manufacturer’s parts site rather than the hardware store.

O-Rings, Washers, and Seals — Where Drips Actually Come From

If your faucet is dripping, the odds are overwhelming that one of these tiny rubber faucet replacement parts is the cause. Home Depot’s plumbing guidance puts it directly: “a worn-out washer or gasket, a loose O-ring, or corrosion in the valve seat” are the most common sources of a leaking faucet.

O-rings are circular rubber gaskets that seal moving parts — most commonly around the base of a swiveling spout or under a handle. When the spout starts dripping at the base (water seeping where the spout meets the deck), the O-ring underneath has lost its seal. They cost almost nothing — an assortment bag of 20+ sizes runs $5–$10 — and replacing one is a 10-minute job once you’ve got the faucet apart.

Washers are flat rubber or nylon discs found in older compression-type faucets (the kind where each handle visibly tightens against a seat to shut off water). Compression faucets are the design Grandma’s house had; they’re still common in homes built before about 1985. Each handle has a washer that compresses against a metal seat when you close the tap. After years of compression cycles, the washer hardens, cracks, or wears thin — and you get a drip from the spout that no amount of tightening fixes.

Seals and gaskets are the umbrella category for everything else: silicone O-rings inside cartridges, rubber gaskets under the faucet base that seal it against the sink deck, and the various small seals inside diverter valves on pull-down sprayers. Most are generic and sold in multi-packs at hardware stores for under $10.

These are the cheapest faucet replacement parts in your toolkit and the ones that fail most often. Stock a multi-size bag and you’ll save yourself a Home Depot run on the next drip.

Springs and Valve Seats — For Older Two-Handle Faucets

If you have a Delta two-handle faucet (the rotating-ball or compression style with separate hot and cold knobs), you have springs and valve seats — the faucet replacement parts specific to this older valve architecture — to keep on the radar. These are the small metal components that sit under the cartridge or washer. The spring provides the upward force; the seat is the metal surface the rubber compresses against.

Seats corrode over years of water flow. Even a brand-new washer won’t seal against a corroded seat, which is why Delta sells the pair together: RP4993 is listed by Delta as “Seats & Springs (2 ea)”, and the more comprehensive RP28603 repair kit adds the other wear parts — replacing the rubber alone often doesn’t fix the leak.

Seat-and-spring kits run $5–$15 at Home Depot, Lowe’s, or any plumbing supply store. They’re brand-specific within Delta’s range but most Delta two-handle faucets share compatible parts. For Moen, Kohler, or Pfister equivalents, search by faucet model — these brands use different valve architectures and the parts aren’t interchangeable.

Supply Lines, Nuts, and Hardware — The Stuff Under the Sink

Above the sink is what you see. Below it is where the faucet attaches to your home’s plumbing — and where a different category of failure happens.

Supply lines are the faucet replacement parts located under the sink — flexible braided hoses (occasionally older plastic ones) that carry water from your shutoff valves up to the faucet. They use 3/8″ compression fittings at one end and 1/2″ at the other, which is the universal standard for residential faucets. Braided stainless steel supply lines last 10–15 years and cost about $10 each. If yours are plastic or older than a decade, replace them proactively — a burst supply line at 3am floods a kitchen before you wake up.

Mounting nuts and brackets are the large nuts under the sink that clamp the faucet body to the sink deck. They rarely fail, but when they do — usually from rust on an old faucet — you’ll need a replacement matched to your faucet’s shank diameter. A basin wrench is the only practical tool to reach them; see the Pillar 1 faucet repair guide for the full tool list.

Diverters and spray hoses are pull-down or side-spray-specific faucet replacement parts. These wear out in heavy-use kitchen faucets after 5–10 years and are usually brand-specific. Moen and Delta both sell their own diverter replacements; expect to spend $15–$30 for an OEM part.

Universal vs. Brand-Specific Faucet Replacement Parts

The single most important sorting question when you’re buying faucet replacement parts: is this part universal (any brand will work) or brand-specific (must match your exact faucet model)?

Here’s the short version:

Part	Universal or Brand-Specific
O-rings, washers, gaskets	Universal (sized by diameter)
Aerators (most)	Universal (15/16″ male or 55/64″ female)
Supply lines	Universal (3/8″ compression standard)
Plumber’s tape, putty, silicone	Universal
Cartridges and valve stems	Brand-specific (and often model-specific within brand)
Springs and valve seats	Brand-specific
Handles and knobs	Brand-specific
Escutcheons and trim plates	Brand-specific (and finish-matched)
Diverters and spray heads	Brand-specific

If a part has rubber that compresses or a generic thread that screws in, it’s probably universal. If it engages with the internal mechanism of the faucet — fits inside the valve body, mates to a manufacturer’s specific port arrangement, or has a decorative finish that needs to match — assume brand-specific until you’ve confirmed otherwise.

The practical implication: stock universal parts heavily (they’re cheap and they fit anything you’ll ever own), and only stock brand-specific cartridges and rebuild kits for the exact faucets in your house.

What to Keep in Your Spare Parts Drawer

The DIY plumbing consensus, drawn from manufacturer documentation and trade resources, is that homeowners should keep five faucet replacement parts on hand at all times. If you own your home and the faucets are more than five years old, you’ll use all five within the next decade.

Assorted O-ring and washer pack ($5–$10). Plumbing-grade multi-size assortment. Worn seals top the failure chart, every source agrees.
One spare aerator each for kitchen and bath ($6–$12 total). Cheap insurance against clogs.
Brand-matched rebuild kit for your specific faucets ($5–$30 depending on brand). For Moen single-handle made before about 2009: a spare 1225 cartridge – newer models use different cartridges, so confirm on Moen’s parts site first. For Delta two-handle: RP4993 (Delta’s “Seats & Springs (2 ea)”) or the fuller RP28603 repair kit. For Kohler: identify your model first, then buy the matching rebuild kit from Kohler’s site.
One spare braided supply hose ($10). Add a second if your existing lines are older than 10 years.
Plumber’s tape and silicone sealant ($5 combined). For every reassembly.

Total spend on these faucet replacement parts: roughly $30–$70 depending on which brand-specific kit you stock. That’s less than a single after-hours plumber call.

Where to Buy Faucet Replacement Parts (Same-Day vs. Online)

Big-box stores (Home Depot, Lowe’s) carry the largest retail selection of faucet replacement parts. Both stock house-brand basin wrenches and tools, generic O-rings and washers, Danco rebuild kits, common Moen cartridges (1225 is usually on the shelf), Delta seat-and-spring kits, supply lines, and a wide aerator selection. Same-day pickup on most items.

Hardware store chains (Ace, True Value) carry the universal faucet replacement parts well: aerators, O-rings, washers, supply lines, plumber’s tape. They may carry a few brand-name cartridges if popular but not a full catalog. Good for emergency runs when the big-box is too far.

Plumbing specialty stores (Ferguson, plumbing wholesale) stock virtually every OEM faucet replacement parts option across Delta, Moen, Kohler, and Pfister — but prices run higher and many require trade accounts. Useful for rare or older parts.

Online (Amazon, manufacturer sites, PlumbingSupply.com) is where rare or model-specific faucet replacement parts live. Amazon Prime delivers stocked items in a day; Home Depot and Lowe’s ship in 1–3 days; manufacturer direct shipping runs 2–5 days. For brand-name parts you can’t find locally, the manufacturer’s own site is usually the most reliable source for authenticity — counterfeits of Moen and Delta cartridges are a real problem on Amazon’s third-party marketplace.

If your faucet is under the manufacturer’s Limited Lifetime Warranty (Moen, Kohler, and Delta all offer one for original homeowners), call the manufacturer’s customer service before you buy. They’ll often ship replacement cartridges and other faucet replacement parts free of charge — see the complete faucet repair guide for the warranty details.

Quick Reference — Faucet Replacement Parts at a Glance

Part	Typical Lifespan	2026 Cost	Universal?	Where to Buy
Cartridge / valve stem	8–15 years	$15–$50	Brand-specific	Home Depot, Lowe’s, manufacturer
Aerator	Indefinite (clogs, doesn’t fail)	$3–$10	Mostly universal	Any hardware store
O-rings / washers / seals	5–10 years	$5–$10 (assortment)	Universal	Any hardware store
Springs and valve seats	10–15 years	$5–$15 (kit)	Brand-specific	Home Depot, Lowe’s
Supply lines (braided)	10–15 years	$10 each	Universal (3/8″ comp)	Any hardware store
Mounting nuts	Indefinite	$5–$15	Brand-specific by shank	Specialty plumbing
Diverter / spray hose	5–10 years	$15–$30	Brand-specific	Manufacturer or specialty
Handles / knobs	15+ years	$15–$50	Brand-specific	Manufacturer

What’s Next

If you’re shopping for specific faucet replacement parts right now, the first step is always brand and model identification — the wrong cartridge is a $25 mistake. Start with the brand identification guide if you don’t already know what’s under your sink.

If you’re troubleshooting a drip and trying to figure out which part to replace, the diagnostic guide walks through the six most common causes with a symptom-to-cause shortcut.

And if you want the broader context — types of faucets, tools required, when to DIY vs. call a plumber — the complete faucet repair guide is the hub article that links it all together.

Brand-specific cartridge replacement guides for Delta, Moen, and Kohler — plus deeper dives on individual faucet replacement parts — are coming in the next few weeks. Sign up for the email list below and you’ll get each one the week it publishes.

What is the round screen at the tip of my faucet called?

That is the aerator – the screw-on screen at the very end of the spout that mixes air into the stream. It is the part homeowners most often replace without knowing its name, and it is the first thing to check when flow drops off or the faucet starts spitting. If you cannot see threads at the tip, it is probably a recessed (cache) aerator that keys out from underneath. Most take a standard size and a universal aerator key, about $10 to $15 at any hardware store; only a few designer or pull-down spray heads are genuinely proprietary and need the manufacturer’s parts site.

How do I tell an O-ring from a washer?

Shape and location. An O-ring is a round rubber ring that seals a moving part – most often the base of a swiveling spout or the underside of a handle – so a leak seeping out where the spout meets the deck points at an O-ring. A washer is a flat rubber or nylon disc that lives inside the handle of an older compression faucet, pressing against a metal seat to shut the water off. If both handles visibly tighten as you close them, you are looking for washers; if the spout swivels and weeps at its base, you are looking for an O-ring.

Are faucet cartridges universal, or do I need my exact brand?

Brand-specific, and usually model-specific inside the brand – a Moen 1225 will not fit a Delta, and buying on visual similarity is how homeowners end up back at the returns counter. Even a widely used part number is tied to a family and a vintage: Moen describes the 1225 as “commonly used in Moen single handle faucets produced prior to 2009 (date varies based on style and model)” (Moen), and Delta lists the RP19804 for Monitor 1300/1400 Series tub and showers produced before March 2006 (Delta). Identify the faucet first, then order the part.

Which faucet replacement parts actually are universal?

The ones sized by dimension rather than matched to a valve: O-rings and washers, sold by diameter in multi-size assortments; most aerators, which use a 15/16-inch male or 55/64-inch female thread; and supply lines, where 3/8-inch compression is the residential standard. Anything that engages the inside of the valve body – cartridges, springs and seats, diverters – is brand-specific, and so is anything with a finish that has to match, like handles and trim plates.

What should I bring to the store when I do not know what the part is called?

Bring the old part itself, plus the faucet’s brand and model number if you can find them – the model number is what turns “some kind of cartridge” into one SKU. For the universal parts, bring a measurement instead: the aerator’s thread size, the O-ring’s diameter, or the length of the supply line you are replacing. If you do not know the brand yet, work through the brand identification guide before you leave the house, because a cartridge bought on looks is a second trip.

Can I get a replacement part free under the faucet’s warranty?

Sometimes. Delta’s warranty runs to the original consumer purchaser “for as long as the original consumer purchaser owns the home in which the faucet was first installed,” it is explicitly not transferable, and it covers defects in material and workmanship rather than reasonable wear and tear (Delta). So if you bought the house with the faucet already in it, assume you are buying the part – and a cartridge worn out after fifteen years is wear, not a defect. It still costs nothing to check your own manufacturer’s warranty page before you pay.

Sources

Home Depot — How to Repair a Leaky Faucet — diagnostic guidance on washer, O-ring, and valve seat failure
Kohler — Faucet Parts Catalog — OEM parts and category definitions
Lowe’s — Faucet Parts & Repair — retail availability for aerators, cartridges, washers, O-rings
EPA WaterSense — Bathroom Faucets — efficiency standards driving aerator GPM specs
Moen — Replacement Parts Catalog — OEM cartridge and rebuild kit specifications
Delta Faucet — Repair Parts Finder — Delta-specific cartridge, seat, and spring identification
Delta Faucet – RP19804 Monitor Cartridge – stated fitment for Monitor 1300/1400 Series tub and showers before March 2006
Delta Faucet – Limited Warranty – original-owner coverage and free-of-charge replacement parts
Moen – 1225 Cartridge: Kitchen Faucet – which Moen single-handle faucets the 1225 fits

Educational content only. Not a substitute for licensed professional advice. Local plumbing codes vary by jurisdiction. Use of any guidance from this guide is at your own risk.

Get the homeowner’s plumbing repair toolkit checklist — the tools, parts, and decisions every homeowner should have on hand. [Free download — enter your email]

Parts for this repair

As an Amazon Associate, plumbingbythebook earns from qualifying purchases. Links below are affiliate links — they cost you nothing extra.

Faucet O-Ring and Washer Assortment Kit — Worn seals are the most common cause of faucet drips — a multi-size assortment covers O-rings, flat washers, and silicone gaskets for almost any repair.
Moen 1225 Single-Handle Faucet Cartridge — The most common cartridge in Moen single-handle kitchen and bath faucets made before about 2009 — confirm your faucet's vintage on Moen's parts site before stocking one.
Braided Stainless Steel Faucet Supply Hose (3/8 inch) — Replace proactively if your supply lines are plastic or older than ten years — a burst line can flood a kitchen before you wake up.
Basin Wrench — The only practical tool to reach under-sink mounting nuts — essential for faucet installation or removal.

Free download

Get the homeowner's plumbing repair toolkit checklist.

The tools, parts, and decisions every homeowner should have on hand. Free, no spam.

Download the free checklist (PDF)

Free, no email required right now. No spam, ever.