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Flapper for Toto THU138S

Bright red rubber toilet flapper with chain.

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“Love Noel's Plumbing Supply! They are one of my favorite oddball plumbing parts purveyors. As a professional plumber, I rely on sites like Noel's to keep antique and rare fixtures alive. My customers and I are so grateful! ”
-Danielle E.
03/25/2026

$14.87

 

The TOTO THU138S is a highly popular 3-inch toilet flapper designed specifically for TOTO’s G-Max flushing system. It controls the water release during a flush and prevents continuous leaks into the bowl.

We can ship anywhere the US Postal Service ships. For orders being shipped outside the US, please contact us at (888) ASK-NOEL, asknoel@noelsplumbingsupply.com, or via the text widget on this screen.

SKU: 15321 Category: Tags: ,

Stop your toilet from running and cut down on water waste with the TOTO THU138S 3-Inch Toilet Flapper Replacement.

 

THU138S

 

  • Fits popular tank models including the ST743S, ST744S, ST754SF, ST764S, ST774S, and several others.

 

Customer submitted image. 

 

Common questions about this product

Will this item replace the original OEM part? chevron-icon

Yes, this aftermarket part will replace your OEM part. 

Is this the correct item for my application? chevron-icon

If you’re not sure text us a picture 1-888-275-6635 or email us a picture at noelsplumbingsupply@fuse.net.

 

We will make sure you have the right part.

 

 

chat iconWHAT OUR CUSTOMERS SAY…

“Thank you for exact part. Just received and replaced and worked out great! ”
-Karl D.
09/05/2025
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