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Flapper for Toto THU138S

Bright red rubber toilet flapper with chain.

chat iconWHAT OUR CUSTOMERS SAY…

“This place is amazing. I live in San Antonio, Texas and there are a few plumbing stores with vintage parts but they never have what I need and the ordering process takes them weeks. I found a rare part at Noels by reverse image search but they will do it for you. I've used them 3 times. Their agents are knowledgable and polite. They will find you the same part or the after market part and get you going on your way. They have 2-3 day shipping. My house was built in the 30's and they know exactly what the after market parts are that I need. I save money and time going to them. I sure wish they were in San Antonio! I will just go directly to Noel's next time - they are LEGENDS! ”
-BP W.
06/21/2026

$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…

“The vacuum breaker on my outdoor spigot failed and Noel's Plumbing was the only placeI could find that had the appropriate mfr. part. I sent a text with photos on Wednesday evening to make sure the part I found was correct. In less than 2 hours later, I had a reply confirming it was the correct part. Placed my order that evening and received the part on Saturday afternoon (about 2.75 days) and my plumbing issue was resolved! I highly recommend - I really appreciated the prompt and pleasant response. ”
-Kimberly S.
04/25/2026
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