TOTO Washlet+ Aquia IV Dual-Flush + S550e Integrated Smart Toilet Combo

The Washlet+ Aquia IV combo positioning

The Washlet+ Aquia IV + S550e combo (MW4463046CEMGA) pairs the dual-flush Aquia IV bowl with the Washlet S550e electronic seat as a single pre-engineered SKU. At $2,380-$2,880, it's the smart-toilet path for households that want both dual-flush water savings AND full Washlet smart-toilet features — combining Aquia IV's 0.9/1.28 GPF flush with the S550e's heated seat, integrated wash, dryer, and auto-lid.

This combo is the closest path to a Neorest smart-toilet experience for households in space-constrained bathrooms. The Aquia IV's compact-elongated bowl (17.5" front-to-back) fits where a full-elongated Drake II + Washlet combination wouldn't. For apartment / condo / small-bath owners who want smart-toilet features without Neorest's tankless silhouette, this is the right product.

What you get vs Washlet+ Drake combo

The trade-off: Washlet+ Aquia IV gets you dual-flush water savings + compact bowl + Tornado Flush at slightly higher price, BUT with lower MaP score (Aquia IV's 800g vs Drake II's 1,000g+). Choose based on whether dual-flush water savings + compact footprint matter more than maximum flush velocity.

The dual-flush + Washlet integration

The Aquia IV bowl uses TOTO's proprietary dual-flush canister with a top-mount push-button actuator. The Washlet+ designation adds the S550e seat with all its features. Operation:

• Light flush (0.9 GPF): press the smaller button on top of the tank (or use the Washlet remote for auto-flush after seat use).
• Full flush (1.28 GPF): press the larger button.
• Washlet auto-flush: some Washlet+ configurations can trigger flush from the remote — verify the specific SKU.
• Manual flush + Washlet wash + dryer: typical user sequence is sit (heated seat activates), use, press wash button on remote, dryer follows, stand to leave (auto-lid closes), then press tank button to flush.

The S550e features (carried over from Washlet+ Drake combo)

• Heated seat with eco-mode
• Instant-heat water for bidet wash
• Integrated bidet wash (rear, front/feminine, oscillating)
• Warm-air dryer
• Auto open/close lid with motion sensor
• Auto-deodorizer with carbon filter
• EWATER+ pre-use bowl mist sanitization
• Self-cleaning wash nozzle
• Soft-light night LED
• Wireless remote control

For complete feature breakdown, see Washlet+ Drake II combo product page.

The variant matrix

Install requirements

• GFCI outlet within 3 feet of toilet base — required.
• Standard 12" rough-in.
• Total weight: ~130 lbs across two boxes (Aquia IV bowl + tank ~90 lbs; S550e seat ~40 lbs).
• Compact bathroom fit: Aquia IV's 17.5" compact-elongated bowl fits bathrooms where Drake II's 18.5" wouldn't.
• Standard two-piece install — see Aquia IV install.

The total cost picture (US, all-in)

• Washlet+ Aquia IV + S550e combo: $2,380-$2,680
• GFCI outlet installation (if not present): $200-$450
• Wax ring + supplies: $15-$25
• Plumber labor (if not DIY): $250-$450
• Total turnkey: $2,595-$3,605

What owners report

• The compact-elongated bowl is the differentiator from Drake combo. Owners with smaller bathrooms specifically mention that this combo "fit where Drake wouldn't."
• Dual-flush + smart-toilet combination is unique at this price point. No other US smart toilet at $2,500-$2,800 offers both.
• The Aquia IV's dual-flush mechanism + Washlet seat work together cleanly. The push-button dual-flush is on the tank top; the wash/dryer controls are on the wireless remote — no conflict.
• Water savings stack with smart-toilet hygiene benefits. Owners report bowl staying noticeably cleaner due to EWATER+ + paper-use reduction (less paper because of bidet wash).
• MaP 800g is sufficient for normal-use households. Occasional double-flushing on heavy-paper visits, but the Washlet bidet dramatically reduces paper use anyway.
• Service profile: Aquia IV dual-flush canister at 10-12 years ($45 TOTO part); Washlet S550e electronics at 10-15 years ($400-$700 module replacement).

Where Washlet+ Aquia IV wins vs Washlet+ Drake II

• Compact bowl footprint — fits smaller bathrooms
• Dual-flush water savings — 25-30% water reduction
• Tornado Flush technology vs Drake II's Double Cyclone (both premium, slightly different)
• Better suited for apartment/condo installations

Where Washlet+ Drake II wins vs Washlet+ Aquia IV

• Stronger flush MaP score (1,000g+ vs 800g)
• Lower price ($100-$200 less for the combo)
• Full-elongated bowl comfort — 18.5" deep, more comfortable for longer sittings
• Broader retail availability
• Universal flapper parts (Drake II uses standard flapper; Aquia IV uses TOTO-proprietary dual-flush canister)

The verdict

Buy Washlet+ Aquia IV if:

• Bathroom is space-constrained (apartment, condo, smaller-than-standard master bath)
• You want dual-flush water savings stacked with Washlet smart-toilet features
• You're in a rebate-eligible utility district (dual-flush + smart-toilet often qualifies for premium rebate tier)
• The compact-elongated bowl works for your household comfort preferences

Buy Washlet+ Drake II instead if:

• Bathroom has space for full-elongated 18.5" bowl
• Maximum flush MaP score matters more than water-savings dual-flush
• $100-$200 savings is meaningful
• Universal flapper parts ecosystem matters for long-term service

Buy Neorest 700H instead if:

• The tankless integrated silhouette matters
• Foot-sensor flush + dual-flush 0.8/1.0 GPF + ACTILIGHT UV are desired
• $1,500-$2,500 premium over the Washlet+ combo is justifiable

Warranty

TOTO Washlet+ Aquia IV + S550e combo residential warranty: 1 year on tank trim, 2 years on Washlet electronics, lifetime on porcelain. Aquia IV dual-flush canister: 5-year mechanism warranty. Combo administered by TOTO USA as a single SKU.

Pricing reality (2026)

Washlet+ Aquia IV + S550e MW4463046CEMGA (Cotton White Classic): $2,380-$2,680. Ferguson and Build.com Pro Desk: $2,180-$2,380. Home Depot: $2,599-$2,799 standard (limited stock). California utility rebates ($50-$150) drop net cost to $2,230-$2,530 in rebate-eligible zones. Buying Aquia IV + standalone S550e Washlet separately: $580 + $1,650 = $2,230 (saves ~$150 but loses pre-engineered integration).

The honest summary

The Washlet+ Aquia IV combo is the right smart-toilet for the buyer with a smaller bathroom who wants dual-flush water savings stacked with Washlet features. It's a specific niche product — most US households are better served by either the Washlet+ Drake II combo (stronger flush, lower price, full-elongated) or the Neorest 700H (integrated tankless silhouette). For the buyer with a compact-elongated bathroom who values dual-flush + smart features, this combo delivers exactly what's needed.