Kohler Toilet Parts: Model Numbers and Where to Buy

Why Does Kohler Have So Many Different Part Numbers?

Kohler toilets span three generations of flushing technology currently in service: the traditional flapper-and-flush-valve system used in older Wellworth and Highline Classic models, the Class Five pressure-activated canister flush valve introduced in the early 2000s, and the AquaPiston canister introduced around 2010. Each system uses different internal geometry and requires different replacement parts. Knowing which generation your toilet belongs to before ordering is the single most important step in Kohler parts sourcing.

This guide maps the most common Kohler toilet models to their key internal parts, explains OEM versus aftermarket viability for each part category, and lists the best sources for purchasing -- from Kohler's own website to authorized plumbing distributors and online retailers. Where aftermarket parts are safe, they are identified by specific brand and part number. Where OEM is required, the Kohler part number is provided so you can order with confidence.

What Flush Systems Do Kohler Toilets Use and How Do They Affect Parts?

AquaPiston Canister (2010 to present)

The AquaPiston canister is Kohler's current standard flush mechanism for the Cimarron, Highline Classic with AquaPiston, Corbelle, Memoirs Classic, Archer, Santa Rosa, and most other models introduced after approximately 2010. The canister sits vertically in the center of the tank and opens from all 360 degrees when the trip lever is activated, which Kohler's published specifications indicate delivers 90 percent more water flow to the bowl rim compared to a traditional flapper-and-seat configuration. The AquaPiston system earns MaP scores at or near the 1,000-gram maximum on Kohler models tested by the independent MaP flush testing program.

The primary wear part in the AquaPiston system is the canister seal, sold as the Kohler AquaPiston Canister Seal Kit (part 1084439). This seal degrades over time and causes slow dripping from the tank into the bowl, leading to ghost flushing or a constantly running toilet. Kohler also sells the complete AquaPiston Canister Assembly (part K-GP1083167) for cases where the entire tower has cracked or failed mechanically. Neither the seal nor the canister tower has confirmed aftermarket substitutes from third-party suppliers as of June 2026; Kohler OEM is the correct sourcing path for both.

Class Five Canister (early 2000s through 2010)

The Class Five canister system was Kohler's previous generation high-performance mechanism, used in the original Cimarron, Highline Classic, and several commercial-grade models. The Class Five uses a different canister geometry from the AquaPiston. The repair kit is the Class Five Canister Repair Kit (part 1085846), which includes the tower seal and piston assembly. As with the AquaPiston, no aftermarket canister replacement is available, and the OEM kit is the only sourcing option. The Class Five repair kit is available at Home Depot, Lowes, and major plumbing suppliers in most U.S. markets.

Traditional 3-Inch Flapper System

The Kohler Wellworth K-3978 and K-3999, along with several older Highline models and some international-market Kohler toilets, use a conventional 3-inch flapper seated on a 3-inch flush valve seat. The OEM flapper is Kohler part K-84166. Aftermarket alternatives include the Korky 3060BP (3-inch universal), Fluidmaster 5403 (3-inch), and the Danco 88043. These aftermarket flappers are sold at every major hardware retailer and are compatible with Kohler's 3-inch seat without modification. Owner reviews across Home Depot and Amazon confirm these fits for Wellworth and older Highline owners. The Fluidmaster 5403 in particular appears frequently in Wellworth owner Q-and-A sections as a confirmed-compatible, long-lasting alternative.

What Are the Part Numbers for the Most Common Kohler Toilet Models?

Which Kohler Parts Are Safe to Replace With Aftermarket Alternatives?

Fill Valves

Kohler's OEM fill valve for most of its AquaPiston-equipped models is the K-GP1138930. This part uses a float-cup design with a standard 7/8-inch locknut and 3/8-inch compression supply connection -- the same dimensions used by the Fluidmaster 400A, Fluidmaster 400AH, and Korky 528 series. All three aftermarket fill valves are widely confirmed as compatible with Kohler's AquaPiston-equipped tanks in owner reviews at Home Depot and Amazon, and none affect the bowl's WaterSense status. The Fluidmaster 400AH PerforMAX is the most commonly cited aftermarket fill valve for Kohler Cimarron and Highline owners in aggregated Q-and-A sections across major retail platforms.

For the Wellworth's older tank designs, the Fluidmaster 400A and Korky 528 are also confirmed compatible. Kohler no longer manufactures distinct fill valves for each model line; the K-GP1138930 serves as the standard OEM replacement for most current models.

Flappers

Flapper replacement only applies to Kohler models with a traditional flush valve seat rather than an AquaPiston or Class Five canister. The Wellworth K-3978 is the most common flapper-equipped Kohler model in the current residential market. The OEM Kohler flapper (K-84166) is a 3-inch rubber flapper available at Home Depot, Lowes, and most hardware stores. Aftermarket alternatives: Korky 3060BP (3-inch universal, with red silicone option), Fluidmaster 5403. Both are confirmed compatible by Wellworth owners. Do not attempt to install a flapper in an AquaPiston tank -- the canister tower sits where the flapper seat would be, and no standard flapper attaches to it.

AquaPiston Canister Seal Kit (part 1084439)

This is the highest-priority Kohler-specific part for owners of Cimarron, Highline, Corbelle, Santa Rosa, and other post-2010 models. The seal kit replaces the rubber seal and disc assembly inside the AquaPiston tower without requiring removal of the entire canister. Installation typically takes 10 to 15 minutes, involves turning off the water supply, flushing to empty the tank, and pressing the new seal into the tower seat. Kohler's installation guide for the 1084439 is available for download at kohler.com. This kit resolves ghost flushing and running toilets on AquaPiston models in the vast majority of cases. If the canister tower itself has cracked or warped, the complete AquaPiston Canister Assembly (K-GP1083167) is required.

Trip Levers and Handles

Kohler trip levers are semi-interchangeable for functional purposes but model-specific for color and finish matching. Kohler sells trip levers in white (96), biscuit (96), almond (47), black (7), brushed nickel (BN), and polished chrome (CP) among other finishes. A universal chrome trip lever from any plumbing supplier will mechanically fit most Kohler tanks via a standard 5/16-inch nut, but color matching to Kohler's proprietary palette requires the OEM Kohler part. Trip levers for specific models include the K-84998 (Cimarron), K-GP1059692 (Highline), and K-84860 (Wellworth). These are widely available at Home Depot, Lowes, and online.

Toilet Seats

Kohler toilet seats are one of the easiest aftermarket substitutions. Kohler sells its own seat lines (including the Cachet and Reveal series), but any seat with matching elongated or round dimensions and standard 5.5-inch post spacing fits most Kohler elongated and round bowls. The Bemis 200SLOWT is a widely cited aftermarket fit for Kohler Cimarron and Highline elongated models. TOTO's SS154-01 also fits many Kohler elongated bowls. The exception is Kohler's skirted concealed-trapway models (like the Corbelle with skirted base), which may require Kohler-specific seat posts to span the skirted base correctly. Kohler's K-4636-0 is the standard Cachet seat for elongated bowls.

Tank-to-Bowl Gaskets and Bolts

Kohler's tank-to-bowl gasket is a sponge-rubber donut in a standard 3-inch diameter. Universal sponge gaskets from Danco, Harvey's, and Korky are confirmed compatible with all major Kohler two-piece models. Standard 5/16-inch solid brass or stainless-steel tank bolts fit without modification. The OEM Kohler tank-to-bowl bolt and gasket set is sold as part K-GP51491.

Wax Rings

Kohler floor-mount toilets use a standard 4-inch toilet horn, making them fully compatible with any universal wax ring. Harvey's 2-pound wax ring, Fernco's Wax Free Seal, and Danco's Perfect Seal are all appropriate for Kohler installations. Wax rings are the one part category where OEM sourcing provides no advantage over universal alternatives.

Supply Lines

Kohler toilets use a standard 3/8-inch compression inlet on the fill valve and a standard 7/8-inch ballcock-shank connection. Any braided stainless-steel supply line in 12-inch or 16-inch length with 3/8-inch compression by 7/8-inch ballcock fittings is compatible. Fluidmaster's 9 Armada and Watts 8-inch braided supply lines are common choices among plumbers.

Where Can You Buy Genuine Kohler Toilet Parts?

Home Depot and Lowes

For the Cimarron, Highline, Wellworth, Santa Rosa, and Corbelle -- Kohler's highest-volume residential models -- both major home improvement retailers stock the AquaPiston Canister Seal Kit (1084439), the Class Five Canister Repair Kit (1085846), the K-84166 flapper, fill valve K-GP1138930, and an assortment of trip levers in white and chrome. In-store availability is strong enough that same-day emergency repairs are feasible for these models without pre-ordering. For models outside the top-selling tier, in-store stock varies and online ordering through the same retailers is more reliable, typically with free ship-to-store in 3 to 5 days.

Kohler Parts Portal (parts.kohler.com)

Kohler's official parts website is organized by model number and allows searching by the K-number from the toilet's tank lid. The portal shows exploded-view diagrams with labeled parts, which makes it straightforward to identify the correct sub-component even for complex assemblies. Parts ship from Kohler's distribution centers in 3 to 7 business days for standard orders. The site also shows parts availability status, which is useful for older model inquiries. Kohler's customer service line (1-800-456-4537) can assist with parts lookup by model number for owners who prefer phone support.

Browse Kohler replacement parts: Check prices on Amazon

Amazon

Amazon stocks both OEM Kohler parts and compatible aftermarket alternatives in the plumbing section. OEM Kohler parts sold directly by Kohler's brand store on Amazon are reliable; third-party resellers of Kohler parts introduce some risk of mis-labeled or counterfeit components, particularly for the AquaPiston canister seal. Filtering for listings sold or fulfilled by Amazon or sold by Kohler directly reduces this risk. Aftermarket alternatives (Fluidmaster, Korky, Danco) are well-reviewed on Amazon for Kohler applications and ship quickly via Prime for common models. Aggregated owner reviews and Q-and-A sections on these listings are a useful resource for confirming compatibility with specific Kohler tank models.

Authorized Plumbing Distributors

Ferguson Enterprises, F.W. Webb, Hajoca, and Winsupply all carry Kohler as a full-line authorized brand. Distributor pricing is often below MSRP for the same OEM part, and these suppliers stock the full depth of Kohler's parts catalog including commercial-grade components, discontinued model assemblies, and specialty Veil intelligent toilet service parts. Counter staff at plumbing distributors can pull an exact replacement from a K-number and production date, which is especially useful for models with mid-production part changes. This channel is the most reliable option for parts that Home Depot and Lowes do not stock.

Specialty Online Plumbing Retailers

SupplyHouse.com, PlumbersStock, and Repair Clinic carry Kohler parts with detailed compatibility filters and parts diagrams. These sites are particularly useful for identifying the correct sub-part within a larger assembly -- for example, finding just the fill valve seal rather than the complete fill valve, or the tower cap rather than the complete AquaPiston assembly. Repair Clinic's model-specific parts lookup is well-maintained for Kohler and cross-references multiple production years. For owners of toilets more than 10 years old, specialty retailers often have older inventory that big-box retailers have discontinued.

How Do You Find the Model Number on a Kohler Toilet?

The serial number (distinct from the model number) provides additional detail about the production date and can be used by Kohler's support team to resolve compatibility questions for units with mid-production part changes. The serial number on Kohler toilets follows a format like "9608######" where the first two digits indicate the year of manufacture and the next two digits indicate the month. A toilet with a serial number beginning with "9608" was made in August 1996. This dating matters for flush valve type determination on models that transitioned from flapper-based systems to AquaPiston or Class Five canisters at a production changeover date.

How Do Kohler Parts Compare to TOTO, American Standard, and Gerber?

For homeowners prioritizing long-term parts access, Kohler's retail distribution depth is an advantage. The AquaPiston seal kit and fill valve are available same-day at most Home Depot locations nationally, which means an emergency repair does not require advance ordering or a plumbing distributor account. TOTO's Drake series is also well-supported at retail in major metro markets, but TOTO's one-piece models and Aquia IV dual-flush line require more specific sourcing. American Standard's Champion 4 PowerWash rim system is broadly available at retail but uses a proprietary 4-inch flush valve tower that needs an American Standard-specific canister rather than a standard flapper. Gerber, Swiss Madison, and Woodbridge are better supported through specialty retailers and distributors than through walk-in hardware stores.

For a full comparison of how these brands perform in actual use, the best flushing toilets guide ranks current models by MaP score, GPF, and long-term reliability based on aggregated owner data. For a head-to-head view of Kohler and TOTO specifically, see our Kohler vs American Standard comparison and the TOTO vs Kohler brand comparison.

What Are the Most Common Kohler Toilet Repairs and Which Parts Fix Them?

Running Toilet on AquaPiston Models

A running Kohler Cimarron, Highline, or Corbelle is almost always caused by the AquaPiston canister seal failing to seat completely against the tower seat. The fix is the 1084439 Canister Seal Kit. The repair sequence: shut off the water supply at the angle stop, flush to empty the tank, unclip and lift the canister tower (it releases upward with a quarter-turn on some models or a straight lift on others depending on generation), press out the old disc seal, press the new seal in, reinstall the tower, restore water supply. Total repair time for an experienced homeowner is approximately 15 minutes; for a first-time repair following Kohler's video guide, allow 30 to 45 minutes. If the toilet continues to run after seal replacement, the canister tower may have a hairline crack at the base, which requires the complete AquaPiston Assembly (K-GP1083167).

Running Toilet on Wellworth (Flapper Models)

The Wellworth K-3978 and related flapper-based models run when the flapper degrades and no longer seats against the flush valve seat. Confirm with the food-coloring dye test: add a few drops of food dye to the tank, do not flush, and wait 15 minutes. If color appears in the bowl, the flapper is not sealing. Replace with OEM K-84166 or aftermarket Korky 3060BP or Fluidmaster 5403. If the flapper is intact and the dye test is clean, the fill valve may be overflowing into the overflow tube, which means the fill valve needs adjustment or replacement (Fluidmaster 400AH resolves this in most cases). For a step-by-step repair reference, see our how to fix a running toilet guide.

Ghost Flushing

Ghost flushing -- where the toilet briefly refills on its own without being flushed -- is the early stage of the same failure that causes a running toilet. Water is leaking slowly from the tank into the bowl. When the leak depletes enough water to trigger the fill valve, the tank refills in a brief ghost flush cycle. The same parts fix it: AquaPiston seal kit on canister models, flapper replacement on Wellworth and flapper-based models. Ghost flushing can waste 200 gallons or more per day, so timely repair produces a direct reduction in the water bill.

Weak or Incomplete Flush

A weak flush on a Kohler AquaPiston model is rarely a parts failure. More commonly it reflects one of three conditions: (1) the fill valve is set to a water level below the marked waterline inside the tank, causing inadequate flush volume; (2) mineral deposits from hard water have partially blocked the rim jets around the bowl rim, reducing bowl wash during the flush cycle; or (3) the AquaPiston canister tower is not opening fully because the trip-lever chain is too short or the chain is tangled. Adjusting the fill valve's water level to the tank's "fill to here" mark, cleaning the rim jets with a wire brush and diluted CLR solution, and checking the chain length covers all three causes. If none of these resolve it, a crack in the AquaPiston tower may be restricting flow, in which case the K-GP1083167 canister assembly is required. For more detail, see our guide on how to improve toilet flush power.

Fill Valve Replacement

Kohler fill valves last 7 to 10 years under normal use before diaphragm wear causes slow fill or erratic refill noise. Signs of a failing fill valve include a hissing sound after the tank reaches full, very slow refill after a flush, or intermittent refill cycles that activate without a flush. Replacement with the OEM K-GP1138930 or aftermarket Fluidmaster 400AH takes approximately 20 minutes: shut off water, flush, disconnect the supply line at the tank bottom, unscrew the locknut, pull out the old valve, drop in the new valve, set the height to the tank's maximum fill line, reconnect supply line, and restore water. Full step-by-step detail is in our how to replace a toilet fill valve guide.

Kohler Warranty Coverage and Parts

Kohler offers a limited lifetime warranty on vitreous china toilet bowls and tanks for the original purchaser for residential use. This is one of the strongest warranties in the toilet industry and applies to the ceramic against defects in materials and workmanship for the life of the product. Mechanical internal components (fill valve, flush valve, flapper, trip lever, seat) carry a one-year limited warranty for residential use and a one-year warranty for commercial use.

Installing aftermarket parts does not void Kohler's lifetime warranty on the ceramic. However, if an aftermarket internal component causes damage to another part of the toilet -- for example, if a poorly fitting canister seal erodes the flush valve seat -- Kohler may decline warranty coverage for the damaged component while honoring a separate ceramic warranty claim. In practice, this distinction matters most for AquaPiston canister and Class Five canister components, where Kohler specifically recommends OEM replacement kits. For flappers, fill valves, seats, and supply lines, using aftermarket alternatives carries no meaningful warranty risk.

Kohler's Veil intelligent toilet (K-5401) and K-3818 Veil with integrated bidet seat carry a separate one-year warranty on electronic components. This warranty is voided by unauthorized service or non-OEM electronic parts. Veil electronic components should go through Kohler's authorized service network for any repair beyond the cleaning and maintenance steps described in the owner manual. For more detail on warranty terms across brands, see our toilet warranty comparison.

Kohler Model Color and Finish Reference for Parts Matching

Kohler sells its toilets and parts in a range of standard colors, and color matching for trip levers, seats, and tank lids is one of the most common sourcing questions. Kohler's color codes are standard across the product line:

• 0 / White: Kohler White (the standard bright white, matching most other manufacturers' white)
• 96 / Biscuit: A warm off-white, not interchangeable with Kohler White or with other brands' "biscuit"
• 47 / Almond: A medium beige tone, common on toilets installed in the 1980s through early 2000s
• NY / Dune: A deeper beige, used in select mid-century installations
• 7 / Black Black: A true matte black, used on the Cimarron and Memoirs in black finish variants

When replacing a trip lever, seat, or tank lid on a colored Kohler toilet, ordering by the Kohler color code ensures a match. Hardware store staff can look up parts by color code, or Kohler's parts portal allows filtering by color. Mis-matching a white (0) part to a biscuit (96) toilet is one of the most common visual errors in Kohler toilet repairs.