For a skirted toilet with the seat included, pick the TOTO Aquia IV Cube. For chair height with seat and wax ring, the American Standard H2Option. For a skirted toilet with no floor drilling, the Kohler Persuade Curv.
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This guide compares three two-piece dual flush toilets using TOTO, American Standard and Kohler spec sheets.
Dual flush toilets compared (maker spec sheets)
On a phone, swipe or scroll the table sideways to see every column.
| Model | Full / light flush | Trapway | Seat | Skirted |
|---|---|---|---|---|
| TOTO Aquia IV Cube MS436124CEMFGN | 1.28 / 0.9 gpf | 2-1/4 in. | SoftClose included | Yes |
| American Standard H2Option 606AA002 | 1.28 / 0.92 gpf | 2 in. | Included | No |
| Kohler Persuade Curv K-6355-0 | 1.6 / 1.0 gpf | 2 in. | Sold separately | Yes |
A dual flush toilet has two buttons or settings: a full flush for solids and a smaller flush for liquids. The light flush is what saves water over a single-flush toilet. All three here are two-piece, elongated and built for a standard 12-inch rough-in. For a one-piece design, see our one-piece toilet guide; for all toilet types, our toilet guide.
TOTO Aquia IV Cube MS436124CEMFGN: skirted, seat included
Choose the Aquia IV Cube for a skirted dual flush toilet with the seat in the box. TOTO’s spec sheet (totousa.com) lists a 1.28 and 0.9 gpf dual flush with Dynamax Tornado Flush, CEFIONTECT glaze, a completely skirted bowl, Universal Height, an elongated bowl and an included SS124 SoftClose seat. It is designed to accept a WASHLET+ seat, with an adapter listed as required.
The specification table lists a 2-1/4-inch trap diameter, a 7 by 5-inch water surface, 8 psi minimum flowing pressure, a 12-inch rough-in with 10- and 14-inch Unifit options, and a one-year limited warranty. The drawing shows a 17-9/16-inch seat height and a 27-9/16-inch depth. On October 15, 2026, the standard new offer sold by Amazon.com was in stock with model MS436124CEMFGN#01. For more TOTO choices, see our TOTO toilet guide.
Check TOTO Aquia IV Cube MS436124CEMFGN dual flush toilet on Amazon →
American Standard H2Option 606AA002: chair height, seat and wax ring
Choose the H2Option for a chair-height dual flush with the seat and wax ring included. American Standard’s product page (americanstandard-us.com) for 606AA002 lists a 1.28 gpf full flush and a 0.92 gpf light flush from a push button on the tank lid, a 16-1/2-inch chair-height bowl and an elongated shape, and its title names a seat and wax ring.
The page links a spec sheet (lixil.cdn.celum.cloud) for the earlier 2886.218 model number. That sheet lists vitreous china, an elongated siphon-action bowl with a direct-fed jet, a fully glazed 2-inch trapway, a 9 by 8-inch water surface, a 12-inch rough-in, a 29-3/4 by 15 by 31-1/2-inch size, and a limited lifetime warranty on the chinaware with a five-year limited warranty on mechanical parts. It notes the supply line is sold separately. On October 15, 2026, the standard new offer sold by Amazon.com showed limited stock with model 606AA002.020.
Check American Standard H2Option 606AA002 dual flush toilet on Amazon →
Kohler Persuade Curv K-6355-0: skirted, bolt-free install
Choose the Persuade Curv for a skirted toilet that installs without drilling into the floor. Kohler’s spec sheet (resources.kohler.com) lists a two-piece elongated design with Comfort Height, a top-mount two-button flush of 1.0 or 1.6 gpf, a skirted trapway, and the ReadyLock installation system, which Kohler says avoids drilling into the floor on a standard 12-inch rough-in.
The technical table lists a Class Five flush, a 2-inch trap passageway, a 4-1/2 by 5-3/4-inch water surface, a 16-1/2-inch bowl height in the drawing and a 28-3/16-inch depth. The seat is sold separately, and the sheet says this model cannot use Kohler’s 10- or 14-inch rough-in adapters. On October 15, 2026, the standard new offer sold by eFaucets showed limited stock with model K-6355-0, white. More options in our Kohler toilet guide.
Check Kohler Persuade Curv K-6355-0 dual flush toilet on Amazon →
How much water does dual flush save?
Each toilet’s savings depend on how often the light flush is used. On these sheets the light flush is 0.9 gpf on the TOTO, 0.92 gpf on the American Standard and 1.0 gpf on the Kohler. The full flush is 1.28 gpf on the TOTO and American Standard and 1.6 gpf on the Kohler, the federal maximum set by the Energy Policy Act of 1992, which Kohler lists among its standards. If your area offers toilet rebates, Kohler notes the Persuade Curv is eligible in some municipalities; check with your local water utility.
How you pick the flush differs. Kohler lists a top-mount two-button actuator on the Persuade Curv, and American Standard lists a chrome top-mounted push button on the H2Option. On TOTO’s sheet, check the handle type against the photo on the listing before you buy, since the sheet mentions both a trip lever and a push-button.
Skirted or exposed trapway?
A skirted toilet has smooth sides that hide the trapway curve, so there are fewer ridges to clean around the base. The TOTO and Kohler models here are skirted; the American Standard sheet drawing shows an exposed trapway. Kohler installs the Persuade Curv with its ReadyLock system, which it says removes the need to drill into the floor. For more skirted designs, see our skirted toilet guide.
Seat height and rough-in
TOTO’s drawing shows a 17-9/16-inch seat height on the Aquia IV Cube, measured with its seat. American Standard and Kohler list 16-1/2 inches to the bowl rim, before a seat is added. For more tall options, see our chair-height toilet guide. All three are 12-inch rough-in. TOTO lists 10- and 14-inch Unifit options for the Cube, but Kohler says the Persuade Curv works only at 12 inches; for other rough-ins, see our 10-inch rough-in guide.
Installation notes
Measure the rough-in from the finished wall to the center of the floor bolts before you buy. Kohler’s sheet says to dry fit the toilet if the existing supply stop is closer than 8-1/2 inches to the toilet centerline, since it may need to move. A supply line is listed as sold separately on the American Standard sheet; see our toilet supply line guide. For the floor seal, see our wax ring guide.
Check these before you order
- Flush. 1.28/0.9, 1.28/0.92 or 1.6/1.0 gpf.
- Seat. Included on the TOTO and American Standard; not on the Kohler.
- Skirt. TOTO and Kohler are skirted.
- Rough-in. 12 inches; Kohler has no 10- or 14-inch option.
- Bidet seat. TOTO lists WASHLET+ compatibility with an adapter.
- Seller. Kohler via eFaucets with limited stock.
Which dual flush toilet should you buy?
For a skirted toilet with a seat included and bidet-seat compatibility, the TOTO Aquia IV Cube. For a chair-height dual flush with the seat and wax ring in the box, the American Standard H2Option. For a skirted toilet that installs without drilling into the floor, the Kohler Persuade Curv.
Frequently asked questions
What is a dual flush toilet?
A toilet with two flush settings: a full flush for solids and a smaller flush for liquids.
Which dual flush toilet here uses the least water?
The TOTO Aquia IV Cube, at 0.9 gpf on the light flush and 1.28 gpf on the full flush.
Do these come with a seat?
The TOTO and American Standard include one; the Kohler Persuade Curv does not.
Can I use these on a 10-inch rough-in?
TOTO lists a 10-inch Unifit option for the Cube; Kohler says the Persuade Curv is 12-inch only.
Which ones are skirted?
The TOTO Aquia IV Cube and the Kohler Persuade Curv.
How we chose
This document-based guide makes no hands-on testing claim. We read TOTO’s sheet for the Aquia IV Cube MS436124CEMFGN, the American Standard sheet linked from the H2Option 606AA002 product page, and Kohler’s sheet for the Persuade Curv K-6355. On October 15, 2026, we checked each linked standard new Amazon offer for model, seller, stock and an add-to-cart button. Read our selection method and about Plumbing Picks.
Primary sources
- TOTO MS436124CEMFGN spec sheet (totousa.com): Aquia IV Cube.
- American Standard 606AA002 product page (americanstandard-us.com): H2Option.
- American Standard H2Option spec sheet (2886.218) (lixil.cdn.celum.cloud): linked from 606AA002 page.
- Kohler K-6355 spec sheet (resources.kohler.com): Persuade Curv.