TOTO Flush Valve Tower Compatibility & Replacement Guide

A TOTO toilet that keeps running, or starts trickling again a few minutes after jiggling the handle, almost always points to one part – the flush valve tower.

TOTO moved away from traditional rubber flappers toward canister-style flush towers to get a stronger, more efficient flush while cutting down on the maintenance headaches flappers are known for. The tower design releases water quickly and evenly through a wider opening instead of relying on a flapper hinge to swing clear in time.

Finding the right replacement part can trip people up because TOTO has produced this unit in more than a dozen sizes and thread patterns across its lineup. A tower pulled from a Drake won't drop into an Aquia IV tank no matter how similar the two look sitting side by side. The chart below sorts through that: find your toilet series, and you'll land on the exact tower and gasket it takes, current or discontinued, before you order anything.

Understanding TOTO Flush Tower Components

A TOTO flush tower system is made up of a handful of parts that usually get replaced together or in the same repair visit. Knowing what each one does makes it a lot easier to diagnose what's actually failing.

• The tower/canister: the tall plastic cylinder that sits in the center of the tank and lifts to release water into the bowl when you flush.
• The drain valve: the base unit the tower sits on, which threads into the bottom of the tank through a large mounting nut accessed from underneath.
• The seal gasket: a rubber ring on the underside of the tower or drain valve base that keeps water from seeping past when the tower is seated. This is almost always the actual point of failure in a running toilet.
• The fill valve: a separate component that refills the tank after each flush. It's not part of the tower itself, but TOTO often documents it alongside flush tower parts since both live inside the tank and get serviced around the same time.
• The trip lever and actuator: the mechanism connecting your flush handle to the top of the tower, which lifts it to start the flush.

Most residential leaks and running-toilet complaints trace back to the seal gasket rather than the tower itself, which is why we've listed the correct gasket alongside each flush tower below.

TOTO Flush Valve Tower Compatibility Chart

Match your toilet model to the correct flush valve tower and gasket below. Flush towers are grouped by toilet series rather than by every individual model number, so if your exact model isn't named here, it's almost certainly part of one of these families.

Note: where TOTO's documentation didn't list a specific gasket SKU for a part, that typically means the tower and its seal are sold only as one complete assembly rather than as separate replaceable pieces.

Current / Available TOTO Flush Valve & Tower Applications

Discontinued TOTO Flush Valve & Tower Applications

If your toilet is old enough that you can't find it in either table, that's a sign parts availability is genuinely limited. Reach out to our team with your model number and we'll look into sourcing your part.

How to Replace a TOTO Flush Valve Tower

Every TOTO flush valve tower mounts to the tank the same basic way, through a large plastic nut accessed from underneath the tank. That means the replacement process is nearly identical across the whole lineup, whether you're working on a Drake or an Aquia.

What you'll need: an adjustable wrench, a bucket or towels for residual water, and the correct replacement tower (and gasket, if your model has one separate) from the chart above.

1. Shut off the water supply at the angle stop behind the toilet, then flush and hold the handle down until the tank empties as much as possible.
2. Remove the tank lid and set it somewhere padded to prevent it from chipping.
3. Disconnect the refill tube from the overflow tube at the top of the old tower.
4. Reach into the tank and release the tower from the trip lever or actuator linkage at the top, then twist the tower counter-clockwise (usually about a quarter turn) to unlock it from the base.
5. Reach underneath the tank and unscrew the large mounting nut holding the drain valve base in place. This is the step most people get stuck on, since the nut can be seated tightly and space under the tank is tight to work in.
6. Lift the old drain valve assembly up and out through the inside of the tank.
7. If your model uses a separate gasket, peel the old one off the underside of the base and set the new gasket in place before installing the new tower.
8. Lower the new tower/drain valve assembly into the tank opening and hand-tighten the mounting nut from underneath. Snug it, but don't overtighten since that can crack the tank.
9. Reconnect the trip lever linkage and the refill tube, replace the tank lid, and turn the water supply back on.
10. Let the tank fill, then flush a few times and check underneath the tank for any drips before considering the job done.

If water is still seeping after a fresh install, the most common cause is a gasket that didn't seat flat or a mounting nut that isn't quite snug, not a defective part.

TOTO Flush Tower FAQ

What is a TOTO flush valve tower?

It's the canister-style component that replaced the traditional rubber flapper in TOTO toilets. It sits in the center of the tank, lifts when you flush to release water into the bowl, and reseats itself to stop the flush and let the tank refill.

How do I know which TOTO flush tower replacement part I need?

Match your toilet's model number, usually stamped on the underside of the tank lid or inside the tank itself, against the compatibility chart above. TOTO groups its towers by toilet series, so most models fall clearly into one row.

What are common TOTO flush tower issues?

The most frequent complaint is a toilet that runs constantly or refills itself between uses, which usually means the seal gasket has worn out rather than the tower itself. Weak flushing and a tower that won't fully reseat after a flush are the next most common issues, and both are usually linked to the trip lever linkage rather than the tower.

Can I replace just the gasket instead of the whole flush valve tower?

In many cases, yes. Most current TOTO flush tower systems use a separately sold seal gasket (THU407, 9BU112E-A, or 9BU088E depending on your model), and a worn gasket is the most common point of failure. Some systems, particularly DuoFit in-wall tank units, are sold only as a complete assembly with no separate gasket, which is noted in the chart above.

Are TOTO flush valve tower replacement parts interchangeable between toilet models?

Not usually. Even towers that look similar are sized and threaded for a specific toilet series, and TOTO has revised part numbers over the years as models were updated. Always match against your toilet's exact series or the number stamped on your existing part rather than assuming a similar-looking tower will fit.

Get the Right Flush Tower the First Time

A leaking or weak-flushing TOTO toilet is one of the more straightforward repairs you can do yourself, as long as you start with the correct part. Grab the tower and gasket that actually match your toilet, and the repair that felt like a mystery an hour ago turns into twenty minutes with a wrench.

If your model isn't listed here, or you're not sure which of two similar part numbers applies to your toilet, reach out to our team. We're an authorized TOTO dealer and can help confirm the right part, whether that's by phone at 888-682-5956, email at contact@plumbingdeals.com, or live chat.