Gerber G0099788 3" Flapper for HET Tanks

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Bright blue soft rubber flapper with beaded chain and metal clip.

WHAT OUR CUSTOMERS SAY…

“Sent Noel’s plumbing and image of what was needed, not being able to find it. They had it sent to me within a week and fitment was perfect. 👍 ”

-Lorenzo H.

03/12/2026

$14.27

The Gerber G0099788 & 99-788 is a genuine 3-inch soft toilet flapper designed for high-efficiency toilets (HET).

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The Gerber G0099778 3-Inch Toilet Tank Flapper is a genuine blue rubber replacement part designed to stop toilet leaks, restore flush power, and save water. It is a prime example of a straightforward, tool-free DIY plumbing project that any homeowner can complete.

G0099778 99-778

3-inch diameter (measures approximately 3 and 5/8 inches across the top)
Soft rubber/plastic construction; lacks the extra underside hole found on the Gerber 99-770 model
Fits select 1.28 GPF (gallons per flush) high-efficiency models
Gerber Viper tanks and toilets (such as Gtb20528, Gtb20552, Gtb20562, Gws28590, Gvp28590)
Gerber Maxwell tanks (such as G0028970 and G0028980)