A constantly running toilet can waste water and make an annoying sound, but a worn or poorly sealing flapper is often a simple part to replace. The best toilet flapper for constant running is one that matches your flush valve and toilet model; a wrong-size flapper may not seal, even if it looks close. These five options include standard 2-inch replacements, a model-specific Kohler part, and a larger Kohler flapper. Measure your existing valve and check your toilet’s compatibility before choosing.
Table of Contents
Quick Comparison
| Product | Best suited for | Key detail |
|---|---|---|
| Lydia’s Deal 2-Pack 2-Inch Flapper Kit | Standard 2-inch flush valves | Two rubber flappers with adjustable chains |
| KOHLER GP84995 Hinge Flapper | Compatible Kohler one-piece toilets | Rigid-bar, 2-inch hinge design |
| Korky Classic Plus Red Flapper | Older, higher-flush toilets | Designed to stay open longer; includes chain |
| Chedin 2-Pack Silicone Flappers | Standard 2-inch flush valves | Silicone sealing surface and steel chains |
| KOHLER GP1078441 Class Five Flapper | Listed Kohler two-piece toilets | 3 1/4-inch flapper; currently listed as unavailable |
Our Picks: Best Toilet Flapper For Constant Running reviews
Best Standard 2-Inch Two-Pack: Lydia’s Deal Replacement Kit
This two-pack is a straightforward option if your toilet has a standard 2-inch flush valve. The kit uses flexible, chlorine-resistant rubber and includes stainless steel chains. Its design is intended to cover the valve opening and help restore a seal when an old flapper has hardened, worn, or stopped sitting flat.
Installation is a basic DIY task: remove the old flapper, attach the replacement to the overflow tube, connect the chain to the flush lever, and adjust the chain length. The extra flapper can be kept as a spare or used in another compatible toilet. The key limitation is fit: the product is not for 3-inch flush valves, so measure before ordering rather than relying on the toilet brand alone.
Compared with the Kohler-specific choices below, this kit is a more general replacement. It may suit a home, apartment, or rental property with compatible standard valves, but it is not the best choice when your toilet requires a model-specific hinge or larger flapper.
Pros:
- Includes two replacement flappers
- Flexible, chlorine-resistant rubber construction
- Stainless steel chains allow for chain-length adjustment
- Designed for many standard 2-inch flush valves
Cons:
- Does not fit 3-inch flush valves
- Compatibility still depends on measuring your valve and checking the flapper attachment
Verdict: Choose this kit if you have a standard 2-inch valve and want a simple two-flapper replacement set.
Best for Compatible Kohler One-Piece Toilets: GP84995 Hinge Flapper
The KOHLER GP84995 is a 2-inch hinge-style flapper made for various Kohler one-piece toilets. Its rigid bar is intended to support consistent flushing, while the corrosion-resistant construction is designed for use inside a toilet tank. It is listed for specific models including the Rosario, Rialto, San Raphael, and Revival series.
This part is a better match for an owner who has confirmed the toilet model and needs the hinge-style design than for someone shopping by valve size alone. A flapper can be the right diameter and still have the wrong attachment or shape, so check your existing part and toilet model before buying. Unlike the two-packs in this list, this is a single model-focused replacement.
Pros:
- Genuine Kohler replacement part
- Designed for compatible one-piece toilet models
- Rigid bar supports a consistent hinge-style flush action
- Corrosion-resistant construction
Cons:
- Compatibility is limited to certain Kohler models
- Not a general-purpose choice for every 2-inch valve
Verdict: Consider this flapper when your Kohler one-piece toilet is among the listed compatible models; otherwise, verify the part number before choosing it.
Best for Older High-Flush Toilets: Korky Classic Plus Red Flapper
The Korky Classic Plus is designed to stay open longer for older 5- and 7-gallon-per-flush toilet models. That makes its intended use different from a basic replacement flapper for a modern standard toilet: its flush behavior is tailored to older toilets that may need the flapper to remain raised longer.
It includes a stainless steel chain and a removable collar. The collar allows attachment to brass flush valves and can be removed to fit plastic valves, according to the product information. The flapper is made from Korky’s red Chlorazone rubber. Check your toilet’s model and valve setup before selecting it, especially if you are replacing a flapper in a newer, lower-flush toilet.
Pros:
- Designed for older 5- and 7-gallon-per-flush models
- Includes a stainless steel chain
- Removable collar accommodates brass or plastic flush valves
- Made from red Chlorazone rubber
Cons:
- Its longer-open design may not suit every toilet
- Check valve type and toilet model to confirm fit
Verdict: This is a specialized option worth considering for a compatible older toilet, rather than a default pick for a standard modern toilet.
Best Silicone Two-Pack for Standard Valves: Chedin Replacement Flappers
This two-pack uses a flexible silicone sealing surface and stainless steel chains. It is made for standard 2-inch flush valves and is described as compatible with many models from brands such as Kohler, TOTO, American Standard, Gerber, Mansfield, Delta, and Glacier Bay. Brand names alone do not guarantee a match, so measure the valve and check the existing flapper style.
The package includes two flappers, which can be useful if you maintain more than one compatible toilet or want a spare on hand. Installation follows the familiar process of shutting off the water, draining the tank, removing the old flapper, attaching the new one, and adjusting the chain. As with any replacement, too much slack or too little slack in the chain can affect how the flapper closes and operates.
Compared with the Lydia’s Deal kit, this option offers a silicone sealing surface rather than rubber, while both are intended for standard 2-inch valves and come in a two-pack. It is not suitable for 3-inch valves.
Pros:
- Two flappers included in the kit
- Flexible, chlorine-resistant silicone sealing surface
- Stainless steel chains
- Listed for many standard 2-inch valve models
Cons:
- Not designed for 3-inch flush valves
- Requires careful measurement and chain adjustment for proper operation
Verdict: Choose this kit if your toilet uses a compatible 2-inch valve and you prefer a silicone-seal two-pack.
Best for Listed Kohler Class Five Toilets: GP1078441 Flapper
The GP1078441 is a 3 1/4-inch Kohler flapper made for various two-piece toilets with Class Five technology. Its listed compatible models include certain Memoirs, Bancroft, Devonshire, and Cimarron toilets. This larger size sets it apart from the standard 2-inch options in this guide.
Because this is a model-specific replacement and is listed as currently unavailable, it is best treated as a fit reference rather than an easy-to-buy general option. If your toilet uses this part, confirm the model and check the listing for availability before ordering. A 2-inch replacement should not be used as a substitute just because it is easier to find.
Pros:
- Genuine Kohler part for compatible Class Five toilets
- 3 1/4-inch size suits toilets requiring this larger flapper
- Compatible model list helps narrow down fit
- Corrosion-resistant material
Cons:
- Not a universal flapper
- Listed as unavailable, so it may not be purchasable at this time
Verdict: If your Kohler toilet requires this 3 1/4-inch part, verify the model and current availability; do not choose it for a standard 2-inch valve.
How to Choose a Toilet Flapper for Constant Running
Measure the Flush Valve Opening
Start by checking the size of the flush valve opening beneath the flapper. Many toilets use either a 2-inch or 3-inch flapper, and some model-specific parts are larger still. Measure the opening or compare the old flapper with the replacement specifications. A close-looking size is not enough: a flapper that does not cover the opening properly may fail to seal.
Match the Flapper to Your Toilet Model
Look for the toilet’s brand and model information, often found inside the tank or on the toilet itself. This matters especially for hinge-style flappers and Kohler parts made for specific toilet series. If the model number is hard to find, compare the old part’s shape, attachment points, and size with the replacement details before ordering.
Check the Attachment and Flush Design
Flappers may attach to the overflow tube with ears, a hinge, or another design. They may also be made for a particular flush valve material or a toilet that needs a longer flush. For example, the Korky Classic Plus is designed to stay open longer for certain older toilets, while the Kohler options are tied to specific toilet models. Choose a design that matches the part you are replacing.
Consider the Sealing Material and Chain
These options use rubber or silicone sealing surfaces, and several include a stainless steel chain. Material alone does not guarantee a leak-free fit: the flapper must sit flat on a clean, compatible valve seat. After installation, set the chain so it has enough slack to let the flapper close, but not so much that it catches under the flapper.
Check Whether the Flapper Is the Cause
A running toilet can result from a flapper that is worn, misaligned, or not sealing well, but it is not the only possible cause. Before replacing parts, check whether the chain is caught or holding the flapper open and whether the flapper sits evenly over the valve. If the toilet still runs after a correctly fitted replacement and a chain adjustment, the issue may need further troubleshooting.
Choose a Single Part or a Multi-Pack
A single flapper can make sense when you need a specific replacement for one toilet. A two-pack provides a spare or a second replacement for another compatible toilet, but it is only useful if both toilets take the same size and design. Confirm compatibility for each toilet rather than assuming the same household brand uses the same flapper.
Frequently Asked Questions
Can a worn flapper make a toilet run constantly?
Yes. A flapper that no longer seals well can let water leak from the tank into the bowl, prompting the tank to refill. Check that the flapper fits the valve and sits flat; also make sure the chain is not holding it open.
How do I know whether I need a 2-inch or 3-inch flapper?
Measure the flush valve opening or compare your existing flapper with the replacement specifications. The product descriptions here identify which options are intended for standard 2-inch valves, and the Kohler GP1078441 is listed as 3 1/4 inches. Do not select by brand alone.
Will any 2-inch flapper fit my toilet?
Not always. The valve size is an important first check, but the attachment style and toilet model can also matter. A hinge-style or model-specific toilet may need a particular replacement even if the size seems similar.
How should I adjust the flapper chain?
Connect the chain to the flush lever so it has a little slack when the flapper is closed. If it is too tight, it may keep the flapper from sealing; if it is too loose, it may interfere with the flapper as it closes. Test the flush and adjust as needed.
What if the toilet still runs after I replace the flapper?
First confirm that the new flapper is the correct size, attached correctly, and sitting flat. Check that the chain is not caught or too tight. If those checks do not solve the problem, the cause may be elsewhere in the toilet’s tank components and may need additional troubleshooting.
Is a silicone flapper better than a rubber one?
Material choice is only one part of the decision. The Chedin option uses a silicone sealing surface, while the Lydia’s Deal and Korky options use rubber. The best choice is the one that fits your toilet and seals properly on its valve.
Can I use a 2-inch flapper on a Kohler toilet?
Some Kohler toilets use a 2-inch flapper, but others require a different size or a model-specific design. Check your toilet’s model and existing flapper before choosing a replacement. The Kohler GP84995 and GP1078441 in this guide are intended for different groups of Kohler toilets.
Final Recommendation
For a standard toilet with a measured 2-inch flush valve, the Lydia’s Deal and Chedin two-packs are practical choices, with rubber and silicone sealing options respectively. For a compatible Kohler one-piece toilet, look closely at the GP84995; for a listed Kohler Class Five model, verify whether the GP1078441 is available. If you have an older toilet that needs a longer flush, consider the Korky Classic Plus. In every case, matching the part to your toilet is the most important step toward stopping a flapper-related leak.
