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Flapper for Toto THU138S

Bright red rubber toilet flapper with chain.

chat iconWHAT OUR CUSTOMERS SAY…

“I was very happy with Noel’s Plumbing. I was searching for a fairly rare part and saw it listed on their website. After placing my order, I was informed that the item was actually on backorder. Noel’s Plumbing was upfront and honest right away, letting me know it might take some time to arrive. Throughout the wait, they consistently kept me updated, which I really appreciated. When the part finally came in, they shipped it out immediately. It arrived exactly as described and was precisely what I needed. Excellent communication, honesty, and follow-through. Thank you, Noel’s Plumbing! ”
-Dave F.
04/04/2026

$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…

“Order received and installed. Thank you very much (spoken mentally in my best Elvis voice). Really is nice to know that there is still a business out there that's got their act together! Appreciate the quick service and correct parts shipping. Thanks again.. jP ”
-Jack P.
04/02/2026
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