For owners of specific TOTO tanks, this guide ensures the universal arm and water lines align. We focus on the exact model string for your TOTO Washlet…

By Jonah Reeves · Home editor · Home desk · Gadget Evaluator Lab

Jonah wouldn't reorder this if… Match the TOTO Washlet bidet model number to your tank shape before ordering. The universal arm and water lines must align with your specific TOTO toilet geometry.

The chore here is not comfort; it is mechanical alignment. If the universal arm or water lines do not match your specific TOTO tank shape, the installation fails. You need the exact fit, not a generic guess.

Look at the product photo to verify the model number string. Ensure the TOTO Washlet bidet listing explicitly states compatibility with your tank type before you proceed.

1. Best overall: WASHLET®+ Aquia® IV One-Piece Elongated Dual Flush 1.28 and 0.9…
2. Best value: WASHLET®+ Nexus® One-Piece Elongated 1.28 GPF Toilet with S7A…
3. Upgrade pick: WASHLET®+ Aquia IV® Cube Two-Piece Elongated Dual Flush 1.28 and…
4. Lighter option: Washlet Elongated Bidet Seat with SoftClose Lid T1SW2491#01
5. Spare to keep: WASHLET®+ Nexus® 1G® One-Piece Elongated 1.0 GPF Toilet with S7A…
6. Check the size: Drake® WASHLET®+ Two-Piece Elongated 1.28 GPF TORNADO FLUSH®…
7. Worth a second look: WASHLET®+ Aquia IV® Cube Two-Piece Elongated Dual Flush 1.28 and…
8. Only if it fits: WASHLET®+ UltraMax® II 1G® One-Piece Elongated 1.0 GPF Toilet with…
9. Best overall: WASHLET®+ Nexus® Two-Piece Elongated 1.28 GPF Toilet with Auto…

Best overall

WASHLET®+ Aquia® IV One-Piece Elongated Dual Flush 1.28 and 0.9…

What fitsThis listing specifies the MW646 model number for a one-piece elongated unit with dual flush capabilities at 1.28 and 0.9 GPF, paired with an S7 Contemporary Electric Bidet Seat in Cotton White.

What to checkIn the product photo, verify the tank depth and the specific mounting bracket location on the rear of the one-piece body to ensure your universal arm and water lines align with this tank shape.

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Best value

WASHLET®+ Nexus® One-Piece Elongated 1.28 GPF Toilet with S7A…

What fitsThe title identifies this as the MW6424736CEFG#01 Nexus model, a one-piece elongated toilet rated at 1.28 GPF that includes an S7A Contemporary Bidet Seat in Cotton White.

What to checkCheck the photo for the exact tank geometry and the position of the fill valve inlet, as the one-piece design requires specific line lengths to prevent kinking behind the tank.

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Upgrade pick

WASHLET®+ Aquia IV® Cube Two-Piece Elongated Dual Flush 1.28 and…

What fitsThis is the MW436473 Aquia IV Cube two-piece elongated system with dual flush at 1.28 and 0.9 GPF, featuring an S7A Contemporary Bidet Seat in Cotton White.

What to checkLook at the photo to confirm the tank height and the rear clearance, ensuring the universal arm reaches the flush lever without interfering with the two-piece joint.

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Lighter option

Washlet Elongated Bidet Seat with SoftClose Lid T1SW2491#01

What fitsThe listing details the T1SW2491#01 Washlet seat, which is an elongated bidet seat equipped with a SoftClose lid mechanism.

What to checkExamine the photo for the mounting hole spacing and the water supply inlet location on the side of the seat to verify compatibility with your existing tank's water line routing.

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Spare to keep

WASHLET®+ Nexus® 1G® One-Piece Elongated 1.0 GPF Toilet with S7A…

What fitsThis unit is the MW6424736CUFG#01 Nexus 1G one-piece elongated toilet at 1.0 GPF, bundled with an S7A Contemporary Bidet Seat in Cotton White.

What to checkVerify the tank's rear profile in the image to ensure the universal arm fits the specific one-piece contour and that the water lines do not clash with the integrated design.

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Check the size

Drake® WASHLET®+ Two-Piece Elongated 1.28 GPF TORNADO FLUSH®…

What fitsThe title specifies the MW7764726CEG#01 Drake WASHLET+ two-piece elongated toilet with TORNADO FLUSH technology at 1.28 GPF and an S7 Contemporary Bidet Seat in Cotton White.

What to checkInspect the photo for the tank's rear dimensions and the flush valve position to confirm the universal arm and water lines align with this specific two-piece tank shape.

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Worth a second look

WASHLET®+ Aquia IV® Cube Two-Piece Elongated Dual Flush 1.28 and…

What fitsThis is the MW4364726 Aquia IV Cube two-piece elongated toilet with dual flush at 1.28 and 0.9 GPF, paired with an S7 Contemporary Bidet Seat in Cotton White.

What to checkCheck the image for the tank's rear clearance and the fill valve location to ensure the universal arm and water lines fit the two-piece configuration without obstruction.

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Only if it fits

WASHLET®+ UltraMax® II 1G® One-Piece Elongated 1.0 GPF Toilet with…

What fitsThe listing identifies the MW604 UltraMax II 1G one-piece elongated toilet at 1.0 GPF with Auto Flush, including an S7A Contemporary Bidet Seat in Cotton White.

What to checkLook at the photo to verify the tank's rear shape and the water line inlet position, ensuring the universal arm and lines align with this one-piece tank geometry.

Buy at Amazon

Best overall

WASHLET®+ Nexus® Two-Piece Elongated 1.28 GPF Toilet with Auto…

What fitsThis is the MW4424726CEFGA#01 Nexus two-piece elongated toilet at 1.28 GPF with Auto Flush, featuring an S7 Contemporary Bidet Seat in Cotton White.

What to checkExamine the photo for the tank's rear profile and the flush mechanism location to confirm the universal arm and water lines fit this specific two-piece tank shape.

Buy at Amazon