How to Read a Delta Faucet Model Number: Model vs. Part Number Explained [2026]

Knowing how to read a Delta faucet model number starts with a mistake almost every homeowner makes at least once: typing an RP number into a parts search and assuming it’s the faucet’s model. It isn’t. Delta’s own product page for a kitchen faucet like the 9178-AR-DST lists a whole part list underneath it made up of RP numbers — those are replacement parts tied to that fixture, not the fixture itself. Delta 9178-AR-DST

This guide walks through what a Delta model number actually looks like, where Delta stamps it on kitchen faucets, bathroom faucets, and shower trims, how to tell it apart from an RP part number and a serial number, and what to do when the cartridge generation matters more than any number printed on the trim.

Quick answer — how do I read a Delta faucet model number? A Delta fixture model looks like 9178-AR-DST or T17238: a base number, sometimes a finish code, sometimes a technology suffix. A Delta replacement part number always starts with RP, like RP46074 — that’s a part tied to your fixture, not the fixture’s own model. If you only have an RP number, you have a part number, not a model number.

What you found	What it actually is	Best next step
A number like 9178-AR-DST or T17238	The fixture model number	Search Delta’s parts tool by this number
A number starting with RP, like RP46074	A replacement-part number, not the fixture model	Confirm it’s the correct-generation part before buying
A tag on the cold-water supply line under the sink	Often the easiest place to find the fixture model	Photograph it before you disturb anything
A worn or unreadable cartridge cap	The cartridge generation, not a model number	Match by cap color and cutoff date (pre/post March 2006 for Monitor/MultiChoice)
No numbers anywhere you can find	A missing or removed tag	Use Delta’s lookup tool by feature, or call a plumber

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How to Read a Delta Faucet Model Number: Separate the Model, the Part, and the Serial

Three different identifiers get confused constantly, and separating them is the entire trick. The fixture model number is what Delta calls the faucet itself — something like 9178-AR-DST for a Leland kitchen faucet or T17238 for a Lahara Monitor 17 shower trim. The replacement-part number always begins with RP — RP50587, RP46074, RP19804 — and identifies a specific part sold to repair that fixture, not the fixture as a whole. Delta 9178-AR-DST Delta RP50587 Delta RP46074 Delta RP19804

The third identifier, the serial number, is a separate field entirely. Delta’s product-registration page asks for both a “Product Model Number” and a “Product Serial Number” as distinct entries, which confirms Delta treats these as two different pieces of data — and that warranty claims specifically require the serial number, not just the model. Delta product registration

If you’re staring at a faucet with only an RP number visible — say, because you already pulled the cartridge — you have a part number, not the fixture’s identity. That’s fine for reordering the exact same part, but it won’t tell you the finish, collection, or whether a trim upgrade is compatible. For that, you need the fixture model itself.

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Decode the Segments of a Delta Model Number

The next skill in how to read a Delta faucet model number is breaking the number itself into segments. Once you’ve confirmed you’re looking at a fixture model rather than an RP part, the number usually breaks into readable pieces. Take 9178-AR-DST: the base model is 9178, AR is the finish code, and DST is a technology suffix. Delta’s own product page confirms Arctic Stainless as the selected finish for that listing, which supports reading AR as the finish variant, and the same page attaches DIAMOND Seal Technology to the DST suffix. Delta 9178-AR-DST

Other Delta technology suffixes and feature tags show up the same way across the catalog — MagnaTite docking on pull-down kitchen faucets, ShieldSpray spray pattern, Touch-Clean rubber spray holes, and InnoFlex PEX supply lines on some kitchen models. Delta 9178-AR-DST None of those suffixes are universal codes you can decode with a fixed formula — they’re specific to how Delta names each product line — so the safest approach is always to search the full number as printed, not to guess at what a segment means.

Shower and tub trims follow a different prefix pattern. Delta’s T17238 starts with a T, identifying it as a trim-only model in the Monitor 17 series, with a dual-function pressure-balance cartridge behind it and a MultiChoice Universal rough-in valve ordered separately. Delta T17238 That T prefix is your signal that you’re holding a decorative trim number, not the number for the valve body hidden in the wall — a distinction that matters a lot once you get to ordering parts.

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Where Delta Actually Stamps the Model Number

For a kitchen or bathroom sink faucet, check these spots in order. Start with the visible trim for a logo or collection cue — style and finish alone can narrow the family even with no number visible. Delta 9178-AR-DST Next, check the underside of the sink deck, the supply lines, and any printed tag zip-tied to the hardware, since manufacturer identification data is often kept off the decorative surface entirely and printed on documentation, spec sheets, or a stamped tag instead. Delta product registration Kohler service parts

For a tub or shower valve, the trim plate usually carries a readable model number, but the cartridge generation behind it can still be a separate question. Delta’s T17238 page shows the trim has its own model, while the actual valve type — a pressure-balance cartridge — and the rough-in body are ordered and identified separately. Delta T17238 Delta’s own Q&A for that trim warns that older 1700-series valve bodies still require the older RP32104 cartridge, because the newer cartridge shipped with current trim kits won’t fit an older valve body — proof that the trim’s model number alone doesn’t guarantee cartridge compatibility. Delta T17238

If you can’t find a number on the trim itself, check any paperwork from installation, your online order history, or Delta’s product-registration record if you registered the fixture — all of which ask for the model number as a distinct field you may have already supplied once. Delta product registration

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Use the Cartridge Generation Cutoff When the Trim Alone Isn’t Enough

For Delta Monitor 13/14 tub-shower valves specifically, the cartridge generation matters more than any number stamped on the trim. Delta’s RP19804 page identifies it as the cartridge for 1300/1400 Series tub and shower valves produced before March 2006, while RP46074 is the cartridge for MultiChoice 13/14 Series valves produced after March 2006 — and Delta states plainly that the two are not interchangeable. Delta RP19804 Delta RP46074 The blue-and-white RP19804 and the gray RP46074 are visually distinct for exactly this reason, so photograph the cartridge before you buy a replacement. Delta RP19804 Delta RP46074

Here’s the honest part: Delta doesn’t publish a public formula for decoding a serial number into a manufacture date on its consumer-facing pages. The registration page asks for a serial number strictly to process warranty claims — it doesn’t explain how to read one. Delta product registration So for a Delta shower valve, “before or after March 2006” is a far more useful piece of information than chasing a serial-number decoder that doesn’t exist for homeowners. Delta RP19804 Delta RP46074

If you’re replacing a cartridge and need the full mechanics of that swap — not just identifying which one you need — how to replace a Delta shower cartridge covers the step-by-step.

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Use Delta’s Official Lookup Tool to Confirm the Model

Delta’s “Find Parts and Identify Your Product” tool accepts a known model number in a search box and also offers common-parts-by-issue paths for leaks, hose problems, loose or stiff handles, low flow, touch-technology issues, and general handle trouble. Delta Find Parts and Identify Your Product Its strength is that it ties a confirmed model straight to that fixture’s part list and repair diagram, the same way the 9178-AR-DST product page shows a part list built from RP numbers underneath it. Delta 9178-AR-DST

Its limit is the same one every manufacturer tool shares: knowing how to read a Delta faucet model number still starts with you, not the tool — if you don’t have the model number yet, the tool can’t magically produce one. You still have to identify the fixture by category, visible feature, or symptom first — and for a hidden shower valve, you may still need to confirm the cartridge generation separately. Delta Find Parts and Identify Your Product Delta RP19804

Once you’ve confirmed the model or cartridge number, run it through our free Repair Finder to cross-check the match before you check out — it saves a second trip to the hardware store if the number turns out to be ambiguous.

For comparison, other manufacturers structure this the same general way even though their tools differ: Kohler’s service-parts page walks from product identification to a parts diagram and offers a beta photo-upload tool called Kohler Scout, and Pfister’s replacement-parts page lets you enter a known model number or browse by category, but tells uncertain customers to contact customer service before ordering. Kohler service parts Pfister replacement parts If your fixture turns out to be a different brand entirely, how to identify faucet brand and model covers that broader, cross-brand version of this problem.

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What to Do If You Can’t Find Any Delta Model Number

If every marking is worn off or missing, start with photos before you disassemble anything. Photograph the full fixture, the handle, the escutcheon, the spout, the underside, the supply-line area, and — once removed — the cartridge itself and any stamped numbers on it. Kohler explicitly supports photo-based lookup through Kohler Scout, and Danco advertises a photo-based guide for matching stems and cartridges, which both point to the same practical fallback for a Delta fixture with no visible number. Kohler service parts Danco

Keep the old part in hand until the replacement is confirmed and installed. Delta’s own part pages show that similar-looking cartridges — like RP19804 and RP46074 — are not always interchangeable, so a “close enough” match by eye is a real risk with hidden pressure-balance cartridges specifically. Delta RP19804 Delta RP46074 Generic repair parts from a source like Danco can work for small external items — aerators, O-rings, simple washers — but they’re a poor fit for a hidden cartridge whose generation you can’t confirm. Danco

Replace the whole fixture rather than chasing an identification dead end when the repair would require destructive access, the finish is failing, or the correct cartridge simply can’t be confirmed. Visible signs that lean toward replacement instead of repair include rust at the tap tip, a dull or flaking finish, and leaks that don’t stop after an attempted fix. The Spruce faucet types

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When to Call a Plumber for ID

Call a plumber when identification itself requires real disassembly — shutting off water, freeing a stuck handle, pulling a cartridge, or opening a wall. Delta’s own RP50587 cartridge-replacement guidance mentions shutting off the water, removing the handle with a 1/8-inch Allen wrench, and loosening the bonnet nut with an adjustable wrench — a reasonable point at which an uncertain homeowner should bring in a pro rather than risk live plumbing. Delta RP50587

A short plumber visit can be cheaper than ordering the wrong part twice, especially around a hidden generation cutoff like the one separating RP19804 from RP46074. Delta RP19804 Delta RP46074 Plumber pricing varies a lot by market — The Spruce reports an average hourly cost around $105, with a broader range of $35 to $170, and simple repairs commonly starting around $150 to $190. The Spruce plumber cost A $75–$150 identification-only call is possible in some markets, but treat that as a local low end rather than a guaranteed national price. The Spruce plumber cost

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Quick Decision Tree: Model, Part, or Serial?

1. Is the number stamped or printed on the fixture itself, and does it start with a letter/number combo like 9178-AR-DST or T17238? That’s your fixture model number — search it directly.
2. Does the number start with RP, like RP46074? That’s a replacement-part number, not the fixture model — use it to reorder that exact part, not to identify the fixture.
3. Is it a tub or shower valve with only a trim model visible? Confirm the cartridge generation separately (pre- or post-March 2006 for Monitor/MultiChoice 13/14) before ordering.
4. No number anywhere you can find? Photograph everything and use Delta’s Find Parts and Identify Your Product tool by feature or issue type.
5. Still stuck, or does confirming it require pulling a cartridge or opening a wall? That’s a reasonable point to call a plumber for a short ID visit.

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What’s Next

Now that you know how to read a Delta faucet model number — the fixture model, the RP part number, and, for a shower valve, the cartridge generation — ordering the correct replacement is usually straightforward. For the fuller walkthrough of finding a Delta faucet’s model, trim, and cartridge together, see how to identify your Delta faucet. If your cartridge is out and you’re trying to tell the common Delta families apart by sight, Delta cartridge identification goes deeper on that comparison. And for the cross-brand version of this problem — Kohler, Moen, Pfister, and beyond — how to identify faucet brand and model is the general-purpose guide.

For every other Delta faucet repair once the part is confirmed, the Complete Guide to Faucet Repair — our Pillar 1 hub — covers the four faucet types, the most common failure modes, and when to stop and call a plumber.

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Sources

• Delta – Find Parts and Identify Your Product
• Delta – Product Registration
• Delta – 9178-AR-DST product page
• Delta – T17238 product page
• Delta – RP50587 replacement cartridge
• Delta – RP46074 replacement cartridge
• Delta – RP19804 replacement cartridge
• Kohler – Service & Replacement Parts
• Pfister – Replacement Parts
• Danco – home page (StemFinder and photo-based part matching)
• The Spruce – types of faucets
• The Spruce – how much does a plumber cost

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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.

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