Is the TOTO Aquia IV a Good Toilet?
The TOTO Aquia IV is a good toilet if you want dual flush and a fully skirted base in one fixture, which is the combination this line is built around. TOTO describes the Aquia IV as having a completely skirted design for a sleek and understated look that is easier to clean, and it flushes at 1.28 GPF full and 0.9 GPF reduced.
The flush engine is DYNAMAX TORNADO FLUSH, which TOTO describes as combining powerful bowl cleaning and waste evacuation using water that is 100 percent projected from the rim, creating 360-degree cleaning power. The bowl carries CEFIONTECT, TOTO's ceramic glaze, which TOTO says minimizes waste from sticking to porous ceramic surfaces. TOTO lists the Aquia IV as WaterSense certified and CALGreen compliant. If dual flush is the feature that brought you here, the wider TOTO dual flush range shows what else is built that way.
Arc and Cube are the same toilet with a different tank
TOTO builds the Aquia IV in three tank styles, and the difference is visual. The base Aquia IV uses TOTO's standard tank. The Cube has what TOTO calls a boldly geometric tank for a contemporary look, and the Arc has an elegant flared tank for a transitional one. Both sit on the same elongated skirted bowl, both are Universal Height, and TOTO states both are ADA height compliant with their SoftClose seat or WASHLET. Nothing about the flush, the bowl or the rough-in changes with the tank you pick.
How the Aquia IV compares with TOTO's other skirted lines
The practical difference between the skirted TOTO lines is rough-in flexibility and flush type. The Aquia IV is offered in 12-inch, 10-inch and 14-inch through a Unifit adapter. The Nexus is skirted as well but has no 10-inch version at all, and the Drake covers a 10-inch by being a separate toilet rather than an adapter. If you need a 10-inch rough-in and a dual flush skirted bowl in the same fixture, the Aquia IV is the direct answer.
Does the TOTO Aquia IV Save Water?
The TOTO Aquia IV saves water by giving you two flush volumes instead of one: 1.28 gallons for a full flush and 0.9 gallons for a reduced flush. Federal law has capped toilets at 1.6 gallons since 1994, and the EPA's WaterSense program requires 1.28 or less, so the Aquia IV's full flush already sits at the efficient end before you touch the reduced button.
A lower volume does not mean a weaker flush on a modern TOTO. The current flushing systems, DYNAMAX TORNADO FLUSH among them, were engineered around the lower volume rather than adapted to it. Several states now require 1.28 GPF for new installations, which the 1.28 vs 1.6 GPF guide covers in detail. Several TOTO ranges also offer a 1G version at 1.0 gallons per flush; no Aquia IV is stocked at that volume here, but you can see which lines are in 1 GPF toilets.
How to Choose an Aquia IV
Choosing an Aquia IV comes down to four decisions: one-piece or two-piece, Universal Height or regular height, which rough-in your bathroom actually has, and which WASHLET you want on top. Get those four right and any model in this collection will fit and behave the way you expect.
One-piece or two-piece
Most of the Aquia IV range is two-piece, with a separate tank and bowl bolted together during install. The one-piece fuses them into a single unit. The one-piece looks more streamlined and has fewer seams to wipe around, but it is heavier to carry and set as a single object. The two-piece is easier to handle, easier to service part by part, and it is where the Arc and Cube tank styles live. The flush and the bowl are the same either way. If you are torn, the one-piece vs two-piece comparison works through the trade-offs.
Universal Height or regular height
Universal Height puts the seat about two inches higher than regular height and meets the ADA seat height. Within the Aquia IV, the rest of the toilet does not change with the height: same elongated bowl, same flush, same rough-in options. Taller adults, older users, and anyone with knee, hip or back trouble usually prefer the taller seat, while households with small children often do not. Both heights are in this collection, and the wider tall toilets range shows the same choice across TOTO's other lines.
Measure your rough-in first
Rough-in is the distance from the finished wall to the center of the closet bolts, and it decides whether a toilet physically fits. Twelve inches is the standard Aquia IV configuration, and 10-inch and 14-inch are available using a Unifit adapter, sold separately. Measure to the wall rather than to the baseboard, and use the back pair of bolts if your toilet has four. The rough-in size guide covers the measurement and lists which TOTO series offer which sizes.
Which WASHLET to pair with it
All four WASHLET+ options here (S2, S5, S7 and S7A) include a heated seat, a warm air dryer, a deodorizer, PREMIST and EWATER+, and TOTO's own comparison for these Aquia IV sets lists the S2 and the S5 with the same core function set. The S7 and S7A step up with a slimmer seamless seat, an instantaneous water heater and a night light. The S7A is the only one that opens and closes its lid on a sensor. Buying the WASHLET+ set rather than the bare toilet plus a seat is what hides the power cord and the supply hose.