Most toilet flappers are similar to the standard model introduced in 1954, but manufacturers are adapting them to today's low-flow toilets.
5 Toilet Flapper Types and Two Predecessors To Know
Updated on Aug. 05, 2024
What Is a Toilet Flapper?
As someone who likes to repair toilets, I was taken aback by the idea that there is more than one kind of toilet flapper.
Sure, I’ve seen lots of canisters and tower valves, which are flapper alternatives. But when it comes to the old-fashioned rubber paddle that covers the water outlet in the tank, I always thought that almost all were variations of the universal flapper introduced by Korky in 1954.
Roy Barnes, who operates Maryland-based Service Force Plumbing with his partner Hendrik Vandepoll, is just the guy to help clarify. He confirmed most contemporary flappers are variations of Korky’s design, but it’s a little more complicated than that.
“Many of the flappers appear similar at first glance, but they often have small but significant differences that prevent them from being interchangeable,” Barnes says. “And many manufacturers now make proprietary systems that exclude any type of compatibility.”
Some models break the Korky’s mold because toilet design itself has changed, in a world where water economy is more important than in the 1950s. “These days manufacturers use a variety of flapper systems to achieve the water velocity required for low-flow toilets,” says Barnes. Low-flow toilets, or course, weren’t widely available until the late 1990s.
When choosing a flapper, Barnes says, “The first thing you need to know is the size of the flapper. It should either be a two-inch or a three-inch flapper.” Low-flow toilets typically have three-inch valves to increase water velocity and ensure a clean flush with a limited amount of water.
Without getting into every variation manufacturers devised, here’s a basic rundown of the types of flappers you might find in your toilet.
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Seat Disk
The seat disk predates the Korky flapper, so your toilet must be really old if it has a flush valve that uses one. It’s a flat rubber disk that fits over the valve opening, held in place by water pressure (like a rubber kitchen sink drain-stopping disk).
A chain or rod connects it to the flush handle and lifts it off the valve when you push the handle. It drops back in place when you release the handle.
Seat disks are the original flappers, and they’re still available. But they don’t seal well and take up more space in the toilet tank than contemporary flappers. Any toilet with one is due for a new flush valve or replacement.
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Tank Ball
The rubber tank ball also pre-dates today’s flappers. It fits into the top of the flush valve, with a threaded insertion where you screw a metal rod that attaches to the flush handle. Its shape provides a better seal than a seat disk.
A toilet tank ball — not to be confused with the ball float that controls the fill valve — needs a lot of space, so it works better in an old toilet with a large tank rather than in a newer low-flow model. Standard balls fit most two-inch valves.
Barnes says “new toilets have a three-inch diameter flush valve and flapper” to increase flow rate and provide a better flush, so you’ll need a bigger ball in a low-flow toilet.
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Standard (Universal) Flapper
Korky’s revolutionary flapper, still standard on many toilets, combines the seat disk and tank ball. The flapper is flat on top and bulges into a ball shape on the bottom, with the ball sized to fit inside the flush valve opening.
That’s one innovation. Here’s another: Instead of floating freely in the tank, the standard flapper attaches to the overflow tube. This allows it to “flap” open and closed as the tank empties and refills.
“In the old days,” says Barnes, “most manufacturers used one basic type of flapper despite their own specific model designs. But these days, manufacturers use a variety of flapper systems to achieve the water velocity required for low-flow toilets.
“Any professional plumber will tell you that to get the best seal between flushes, you should always replace a flapper with the exact same flapper.”
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Adjustable Flapper
This is another innovation manufacturers introduced to make flappers better handle water flow. “Many new flappers have a hole in the side of the flapper to enable single-button, dual-flush toilets,” Barnes says. “This gives us the ability to have a No. 1 and a No. 2 flush without needing two buttons on the tank for two different types of events.”
Besides the hole on the side, there’s also one on the bottom. The holes allow water to fill the ball as the tank empties. The fill rate determines how quickly it drops and stops water flow. Some manufacturers provide inserts of varying diameters for the bottom hole, while others provide a ratcheting ring that controls the size of the hole on the side.
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Counterbalanced Flapper
This is another type of adjustable flapper. A standard flapper comes with ears that extend only to the overflow tube, but a counterbalanced flapper’s ears extend several inches beyond the overflow tube and hold a small cup or plate.
The cup fills with water when the tank is full. When the flapper lifts, it provides a counterweight to keep it open. As the water drains out of the cup, it gets lighter, and the flapper eventually closes.
If the flapper has a plate, the pressure of the water in the tank presses it down when the flapper lifts. As the tank empties and the pressure holding the plate decreases, the flapper falls and seals the valve.
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Dual-Flush Flapper
Some toilet manufacturers, like American Standard, make dual-flush toilets with two flush valve openings. One allows for a full flush, the other a partial flush. These toilets require two flappers.
A dual-flush flapper like the American Standard VorMax flapper assembly consists of a pair of flappers connected by a teeter bar. The flush handle controls the teeter bar. Moving the handle in one direction lifts the full-flush flapper, while moving it in the other direction lifts the partial-flush flapper.
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Flush Canister
Many manufacturers replaced flappers on low-flow toilets with tower assemblies that include a canister. A canister is simply a hollow tube that encloses the valve opening and seals it when it’s down. The canister connects to a chain and lifts when you press the flush lever, just like a flapper.
Unlike a flapper, a canister seldom needs to be replaced, but the gasket around the bottom edge does. “If you have a flush canister, like with newer Kohler or American Standard toilets, you will only need to replace the flush gasket specific to that model,” says Barnes.
About the Expert
- Roy Barnes operates Service Force Plumbing with his partner Hendrik Vandepoll. He has 30 years experience in the plumbing trade.
