Choosing between the TOTO Aquia IV and the Nexus one-piece is one of the most common dilemmas for buyers upgrading to a premium skirted toilet — and you deserve a straight answer.
This head-to-head breakdown covers everything you need to pick the right one for your bathroom.
| Feature | TOTO Aquia IV One-Piece | TOTO Nexus One-Piece |
|---|---|---|
| Image |  |
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| Dimensions (L x W x H) | 27-5/8″ x 15-3/16″ x 28-3/8″ | 28-5/8″ x 17-1/2″ x 27″ |
| Flush System | DYNAMAX TORNADO FLUSH | TORNADO FLUSH |
| Flush Rate | Dual: 1.28 / 0.9 GPF | Single: 1.28 GPF |
| CEFIONTECT Glaze | Yes | Yes |
| WASHLET+ Ready | Yes (T40 compatible) | Yes (T40 compatible) |
| Skirted Design | Yes | Yes |
| Rough-In | 12″ (adaptable to 10″ or 14″) | 12″ (adaptable to 10″ or 14″) |
| Buy Now |  |
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1. TOTO Aquia IV One-Piece Elongated Dual Flush Toilet
The TOTO Aquia IV One-Piece brings everything people love about the Aquia IV line — dual-flush efficiency, DYNAMAX TORNADO FLUSH, and CEFIONTECT glaze — into a seamless, one-piece form that’s easier to clean and more premium-looking than its two-piece sibling.
Its slim profile (just 15-3/16″ wide) makes it a great fit for tighter bathrooms, and its WASHLET+ ready design means you can add any top-tier bidet seat with cords and supply lines fully hidden for a clean, integrated look.
Features
- DYNAMAX TORNADO FLUSH with 360° cleaning power and reduced noise
- Dual flush: 1.28 GPF (full) and 0.9 GPF (light rinse) via center-mounted push button
- CEFIONTECT ceramic glaze that resists debris, mold, and staining
- Seamless one-piece skirted design — no tank-to-bowl seam
- TOTO T40 WASHLET+ compatible with fully concealed connections
- Universal height for comfortable use across all ages and abilities
- SoftClose SS234 seat included
- 12″ rough-in; adaptable to 10″ or 14″ with sold-separately adapter
- WaterSense, CALGreen, and CEC certified
Pros
- Dual flush delivers real water savings — 0.9 GPF for most daily flushes adds up significantly over time
- DYNAMAX system is measurably quieter than standard TORNADO FLUSH due to reduced bowl turbulence
- Narrower width (15-3/16″) fits smaller bathrooms more comfortably than the Nexus
- Seamless one-piece body is easy to clean with a single wipe-down
- Generally more affordable than the Nexus for a comparable one-piece configuration
Cons
- Smaller water surface area in the bowl compared to the Nexus — slightly more prone to residue
- Narrower bowl may feel less spacious for larger users
- Dual-flush push button requires a brief learning curve for household guests
The Aquia IV One-Piece is the smart choice if you want a quieter, water-efficient premium toilet that fits neatly into most bathroom layouts and pairs beautifully with any bidet toilet seat upgrade.
Check its current price on Amazon
2. TOTO Nexus One-Piece Elongated 1.28 GPF Toilet
The TOTO Nexus One-Piece is TOTO’s design flagship at this price tier — a wider, more sculptural toilet with a larger water surface in the bowl that keeps things cleaner between flushes and delivers a presence in the bathroom that’s hard to match.
It’s the go-to choice for design-forward renovations and for anyone pairing their toilet with a premium integrated bidet toilet seat setup where the look of the whole unit matters as much as the function.
Features
- TORNADO FLUSH with dual-nozzle centrifugal cleaning action
- Single flush: 1.28 GPF — WaterSense certified
- CEFIONTECT ceramic glaze for a long-lasting, clean bowl surface
- Fully skirted one-piece design with no seams or exposed trapway
- TOTO T40 WASHLET+ compatible — all connections fully concealed
- Universal height, ADA-compliant per spec sheet
- SoftClose seat included
- 12″ rough-in; adaptable to 10″ or 14″
- Wider bowl footprint (17-1/2″) for a more comfortable, spacious seated feel
Pros
- Larger water surface area dramatically reduces skid marks and residue in the bowl
- Wider, more generous bowl is noticeably more comfortable for larger users
- Sleeker, more premium visual profile — a true focal point in any bathroom remodel
- No dual-flush button means a simpler, cleaner tank top for guests
- Pairs especially well with toilet bidet combos and WASHLET+ seats for a spa-like finish
Cons
- Single flush only — no water-saving 0.9 GPF option like the Aquia IV
- Wider footprint (17-1/2″) may be tight in very compact bathrooms
- Typically priced higher than the Aquia IV one-piece for equivalent color configurations
The Nexus is built for buyers who want the most polished, comfortable, and design-forward one-piece toilet in TOTO’s lineup at this price point — and who are happy to trade dual-flush savings for a larger, cleaner bowl.
Check its current price on Amazon
Design & Aesthetics: A Surprisingly Close Contest
Both toilets are fully skirted one-piece units with concealed trapways — so at a glance they look very similar.
The difference shows up in the proportions.
The Nexus is wider (17-1/2″ vs 15-3/16″) and lower-profile in height (27″ vs 28-3/8″), giving it a broader, more grounded stance that reads as more architectural and intentional in a renovated bathroom.
The Aquia IV is taller and slimmer — still premium-looking, but slightly more compact and upright in its silhouette.
If you’re designing around a specific aesthetic and pairing your toilet with a bidet toilet vs bidet seat upgrade, the Nexus simply photographs better and reads as the more premium unit.
Winner: TOTO Nexus
Flush Performance: DYNAMAX vs Standard Tornado
Both toilets use TOTO’s TORNADO FLUSH technology — a dual-nozzle centrifugal system that creates a 360° cyclonic rinse with every flush.
The Aquia IV One-Piece uses the enhanced DYNAMAX variant, which is engineered to reduce water flow turbulence inside the bowl, resulting in a measurably quieter flush.
The Nexus uses the original TORNADO FLUSH — still excellent and far more effective than conventional gravity flush toilets, but without the noise-dampening refinement of DYNAMAX.
For open-plan bathrooms, shared walls, or light sleepers nearby, the Aquia IV’s quieter flush is a genuine quality-of-life win.
Both will handle whatever you throw at them reliably — the real-world difference in cleaning power is negligible for the vast majority of users.
Winner: TOTO Aquia IV (quieter flush via DYNAMAX)
Water Efficiency: Aquia IV Wins Clearly
This is the sharpest dividing line between these two toilets.
The Aquia IV One-Piece lets you choose between 0.9 GPF for liquid waste and 1.28 GPF for solid waste with a simple two-button push.
The Nexus flushes at a fixed 1.28 GPF every single time — no light-rinse option.
Over a household’s daily flush usage, the Aquia IV’s 0.9 GPF option saves a meaningful amount of water and reduces your utility bill over time.
If water efficiency matters to you — whether for environmental reasons or because you live somewhere with water usage restrictions — the Aquia IV is the only logical choice here.
Want to understand exactly how much water a bidet-equipped toilet saves you over time? The dual-flush combination makes the savings even more significant.
Winner: TOTO Aquia IV
Bowl Cleanliness: Nexus Keeps Itself Cleaner
This is a practical point that most buyers only discover after purchase — and it matters more than you’d expect.
The Aquia IV has a narrower water surface in the bowl (approximately 5-5/8″ x 4-1/8″), which means waste has more exposed ceramic to make contact with before reaching the water pool.
The Nexus has a significantly larger water surface (approximately 6-5/8″ x 9-1/8″), which means less residue, fewer skid marks, and a bowl that simply looks cleaner between uses.
If you’ve ever had a toilet that always looks dirty no matter how often you clean it, you’ll immediately appreciate what the Nexus’s wider water pool does for day-to-day maintenance.
Paired with CEFIONTECT glaze on both units, the Nexus turns bowl cleaning into a genuinely low-effort task.
Winner: TOTO Nexus
Comfort & Fit: Depends on Your Bathroom
Both toilets are universal height — typically 16″ to 18″ seat height — which is comfortable for most adults and particularly helpful for seniors or those with mobility considerations looking for the best accessible bathroom setup.
The Nexus’s wider bowl (17-1/2″) gives a more spacious, comfortable seated experience — particularly for larger users.
The Aquia IV’s slimmer footprint (15-3/16″) is a genuine advantage in compact bathrooms where every inch counts.
Measure your rough-in and available side clearance before choosing — the Nexus needs a bit more lateral space to look and feel right.
Winner: Tie — depends on your bathroom dimensions and body type
Verdict — Which One Should You Buy?
Buy the TOTO Aquia IV One-Piece if…
Water efficiency is important to you, your bathroom is on the narrower side, or you want the quietest possible flush in a seamless one-piece package without paying the Nexus premium.
It’s also the smarter pick if you’re budget-conscious and plan to put the savings toward a quality WASHLET+ bidet seat to complete the setup.
Check the TOTO Aquia IV One-Piece on Amazon
Buy the TOTO Nexus One-Piece if…
You want the most visually striking, comfortable, and lowest-maintenance toilet in TOTO’s lineup at this price tier.
The wider bowl, larger water surface, and slightly more architectural profile make it the premium pick for a master bathroom remodel where the toilet is a statement piece as much as a fixture.
Check the TOTO Nexus One-Piece on Amazon
FAQ
Q: Can I use a TOTO WASHLET bidet seat on both the Aquia IV One-Piece and the Nexus?
Yes — both are TOTO T40 WASHLET+ compatible, meaning a WASHLET bidet seat’s water supply line and power cord route through a hidden channel in the bowl for a completely seamless, cord-free look.
This gives you a finish that rivals far more expensive smart toilet combos at a fraction of the cost.
Q: Is the Aquia IV One-Piece’s dual flush easy to use?
Very easy.
A chrome push button sits centered on top of the tank with two distinct button sizes — small for the 0.9 GPF rinse and large for the 1.28 GPF full flush.
Most users have it figured out on their very first visit.
Q: Which toilet is easier to install?
Both are one-piece units and require standard floor bolt installation into a 12″ rough-in.
Because both are single heavy units, you’ll want a second person to help lower them into position safely.
The Nexus is slightly wider and heavier, but the installation process is essentially identical between the two.
Both can be adapted to 10″ or 14″ rough-ins with separately purchased adapters.
Q: Does the Nexus have a better flush than the Aquia IV One-Piece?
Both use TOTO’s TORNADO FLUSH and CEFIONTECT glaze — so cleaning performance is excellent on both units.
The Aquia IV’s DYNAMAX variant is quieter due to reduced turbulence, but the Nexus is not weak by any measure.
The bigger practical difference between them is bowl water coverage: the Nexus’s larger water surface keeps the bowl visibly cleaner between flushes, which many users find more impactful than flush noise.
Conclusion
Both the TOTO Aquia IV One-Piece and the Nexus One-Piece are genuinely premium toilets that will transform your bathroom experience compared to a standard residential unit.
The Aquia IV One-Piece wins on water efficiency, flush quietness, and value — making it the practical premium choice for most households, especially if you’re pairing it with a quality bidet seat and want to keep the total project cost in check.
The Nexus One-Piece wins on aesthetics, bowl cleanliness, and comfort — making it the top pick for a design-forward master bathroom where you want the best-looking, lowest-maintenance setup TOTO makes at this price tier.
Whichever you choose, round out your setup with our bidet toilet seat comparison chart to find the perfect WASHLET+ pairing — and turn your bathroom into something that genuinely feels five-star.
