TOTO Aquia IV Dual-Flush Two-Piece Elongated Toilet

The TOTO Aquia IV positioning

The Aquia IV (MS446124CEMFG for the Cotton White Universal Height variant) is TOTO's volume dual-flush model — the toilet you buy when you want water-saving dual-flush at TOTO performance levels, and when bathroom space is tight enough that the 17.5" compact-elongated bowl matters more than the 18.5" full elongated.

At $478-$580 it sits between the Drake II ($430) and UltraMax II ($820). The premium over Drake II comes from: dual-flush mechanism, compact-elongated bowl design, included SoftClose seat, skirted trapway, and push-button top actuator. If you value water-savings and have a space-constrained bathroom, the Aquia IV is the answer. If neither matters, Drake II is the same TOTO quality for less.

Dual-flush — what it actually saves

The Aquia IV's dual-flush mechanism gives you two flush volumes:

• Light flush (0.9 GPF): press the smaller button. For liquid waste.
• Full flush (1.28 GPF): press the larger button. For solid waste.

For a two-person household using ~70% light flushes and 30% full flushes, average water consumption drops to about 1.04 GPF — vs a 1.28 GPF single-flush toilet at 1.28 GPF average. Over a year, that's roughly 4,300 gallons saved. At typical US water rates ($0.005-$0.015/gallon), savings run $22-$65/year. In drought-rate areas (California, Texas, Arizona) where tiered pricing pushes the marginal water rate to $0.025+/gallon, savings climb to $100-$140/year.

The rebate side is more significant: many California, Arizona, and Texas water utilities offer $50-$150 rebates for dual-flush or sub-1.0-GPF fixtures. Combined with the water-bill savings, payback is typically 2-4 years.

Compact-elongated bowl — the 17.5" middle ground

The Aquia IV uses a compact-elongated bowl — 17.5" front-to-back, between a round-front (16.5") and a full elongated (18.5"). This is TOTO's design move for shoppers in smaller bathrooms who want the comfort of an elongated bowl without the floor footprint. It works:

• Fits in bathrooms with as little as 25-26" floor depth (vs 27-28" needed for full elongated)
• Comfortable for most adults — the 17.5" bowl is closer to elongated than to round in feel
• Standard elongated seats fit (slight overhang ~0.5-0.75")

The Aquia IV is the new-construction default in condos and apartments where bathroom floor plans are tight. Kohler Persuade and American Standard Edgemere are direct competitors in this compact-elongated dual-flush niche.

The dual-flush mechanism — what's different about service

The Aquia IV uses a TOTO-proprietary dual-flush canister inside the tank. Unlike the Drake II's flapper, the Aquia's flush mechanism is a vertical canister that lifts during flush (similar to Kohler's AquaPiston design, but TOTO-engineered for dual-flush). This has implications:

• No traditional flapper to replace. Universal flappers do not fit Aquia IV.
• When the canister wears out (typically 10-12 years), replacement is TOTO part TSU99A.X — about $45. Order from TOTO Customer Service or specialty plumbing supply.
• The dual-flush button actuator on top of the tank is also TOTO-specific. Replacement is $35-55 from TOTO.
• Universal Fluidmaster / Korky parts work for fill valve, tank-to-bowl gasket, supply line, handle. Only the dual-flush mechanism and actuator are TOTO-proprietary.

The push-button actuator — adjustment

The Aquia IV uses a push-button top actuator with two buttons:

• Smaller button on top: light flush (0.9 GPF)
• Larger button on top: full flush (1.28 GPF)

For new owners, the actuator takes a few weeks of habit-formation to remember which button to press. After the learning curve, it becomes automatic. Some Aquia IV owners report initially missing the traditional handle's tactile feedback — there's no flush sensation through a finger like there is with a lever.

Install requirements and procedure

• Rough-in: 12 inches (standard).
• Floor depth needed: the bowl is 25.5" front-to-back. Plan for 18"+ clearance to opposite wall.
• SoftClose seat (SS214 or SS213): included.
• Two-person install recommended — total weight ~95 lbs split across tank (35) and bowl (60).
• Standard wax ring installation. Same procedure as Drake II.
• Tank fills slower than single-flush due to dual-flush mechanism complexity — typically 60-80 seconds for full refill after a full flush.

What owners report — the long-term reality

• The water savings are real and meaningful in California / Arizona / Texas households. Owners with monitored water meters report ~30% reduction in toilet-related water use vs their previous single-flush toilet.
• The 0.9 GPF light flush occasionally requires a second flush for paper-heavy use. Most owners adapt by using the full-flush button when there's more paper. Reports of needing to double-flush for liquid-only use are rare.
• CeFiONtect glaze performs as expected — extended cleaning intervals.
• The dual-flush canister fails at 10-12 years in most reports. Symptoms: phantom flushing, slow flush, or canister won't reset cleanly. Replacement is straightforward — pull old canister, drop new in, no tank removal needed.
• The compact-elongated bowl size genuinely helps in smaller bathrooms. Multiple reviewers mention the toilet fitting where their previous full-elongated didn't.

Where Aquia IV wins vs competitors

The verdict — should you buy an Aquia IV?

Buy if:

• Water conservation matters to you (drought-area resident, rebate-eligible utility, environmental priority)
• Your bathroom is space-constrained and the 17.5" compact-elongated bowl matters
• You want TOTO performance with dual-flush in a single SKU
• You're OK with the proprietary dual-flush canister replacement cost ($45 every ~12 years)

Skip if:

• Dual-flush water savings don't justify the $50-100 premium over Drake II for you
• You prefer traditional lever-handle flush feel over push-button
• You're in a region without water-saving rebates and water is cheap
• Full-elongated comfort matters more than compact-elongated space savings

Warranty

TOTO Aquia IV residential warranty: 1 year on tank trim, lifetime on porcelain. Dual-flush canister carries 5-year mechanism warranty. SoftClose seat: 1 year. Parts through TOTO USA Customer Service; the dual-flush components have ~1-week ship lead time.

Pricing reality (2026)

Aquia IV MS446124CEMFG (Cotton White): $478-$549. Sedona Beige and Bone variants typically +$50. Build.com and Ferguson trade-discount to $458-498. Home Depot stocks at $549 standard. Many California utility rebates ($50-$150) apply, dropping net cost to $330-$430 in rebate-eligible zones.