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Flapper for Toto THU138S

Bright red rubber toilet flapper with chain.

chat iconWHAT OUR CUSTOMERS SAY…

“These people were extremely helpful in taking me through replacing a 25 year old hard water frozen cartridge on my Philrich sink faucet. They were able to identify the correct part I needed from a photo I sent (I had it figured out wrong). I was pleasantly surprised they had an obscure part like this, but they also told me how to extract the old one when I couldn’t get it out. They said to unscrew it after I had concluded from YouTube the old cartridge was supposed to just slide out. It threaded out as they said and saved me buying a cartridge extractor and a hernia. The whole experience has been excellent. ”
-Pete L.
03/10/2026

$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…

“After trying all over my area, I couldn't find the part for the faucet in my older house. The part I needed was found on the first try on their website and ordering was very easy. It was after hours, but someone responded to my text right away. The part was shipped the next business day. After putting the new part in the faucet works better than it has for years! ”
-Mark B.
06/25/2026
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