Toto THU138S 3 Inch Universal Toilet Flapper

Product Description

The TOTO THU138S is a 3-inch toilet flapper designed as an OEM replacement for TOTO toilet tanks. The flapper seals the flush valve opening at the base of the tank, controlling water release during each flush cycle and preventing continuous water loss between flushes. At 0.3 pounds, it is a lightweight, direct-fit component that a licensed plumber or experienced DIYer can swap out quickly during routine toilet maintenance. This part replaces a worn, warped, or leaking original flapper and is a common first step in diagnosing running-toilet complaints.

This flapper is sized for 3-inch flush valve seats, which are standard in many TOTO toilet tank configurations. It is suited for residential bathroom applications and is typically installed during toilet repair service calls where the existing flapper has degraded, cracked, or lost its seal. No special tools are required for installation in most cases, making it a straightforward field repair.

Key Features

• 3-inch seat diameter matches standard TOTO flush valve openings
• OEM replacement part ensures proper fit and seal integrity
• Universal design compatible with common TOTO tank configurations
• Lightweight construction at 0.3 pounds for easy handling and installation
• Direct replacement for worn or leaking original flappers

Compatibility

Designed as an OEM-style replacement flapper for TOTO toilet tanks equipped with a 3-inch flush valve seat. No specific model numbers were provided in the product data; verify the flush valve seat diameter in the tank before ordering.

Installation Notes

Shut off the water supply at the angle stop valve behind the toilet and flush to empty the tank before beginning work. Disconnect the old flapper from the flush valve ears and the lift chain, then seat the new THU138S flapper onto the valve and reconnect the chain with appropriate slack. A licensed plumber should perform this repair in commercial settings or where access is restricted. After installation, restore water supply and verify the flapper seals fully between flushes to confirm no ongoing water loss.

Technical Specifications

• Flapper Seat Size: 3 inches
• Weight: 0.3 pounds
• UPC: 739268 32488 6

Standard Information

• Brand: TOTO
• Manufacturer Part Number: THU138S