Best High Efficiency Toilets (HET): Top WaterSense Models

The Drake II is the HET toilet that most households should buy first. It carries the EPA WaterSense label at 1.28 gallons per flush, achieves a full 1,000-gram MaP score through TOTO's Double Cyclone siphon, and has a large 2 1/8-inch fully glazed trapway that resists clogging across years of heavy use. No other two-piece toilet at this price delivers the same combination of verified water efficiency and top-tier clearing power.

TOTO introduced Double Cyclone flushing on the Drake II to replace a single-hole rim wash with two nozzle jets that spin water around the bowl wall before it enters the trap. The result is a wider, faster siphon column that pulls solids through a 2 1/8-inch glazed trapway on a single 1.28-gallon charge, rather than relying on raw volume. Independent MaP labs rate it at the full 1,000-gram ceiling, and field reports across aggregated owner reviews consistently show near-zero double-flush incidents even in households with four or more daily users.

The Drake II is available in the standard two-piece configuration and in a version with TOTO's SanaGloss (CeFiONtect) glaze, which is an ion-barrier coating fired into the ceramic surface. CeFiONtect reduces surface friction so waste slides cleanly through the bowl and trapway without sticking, which is relevant for HET models because less resistance means a 1.28-gallon flush needs less hydraulic assist to complete the siphon. Owners in hard-water areas report that CeFiONtect bowls stay cleaner longer between scrubbing and resist mineral ring formation. Learn more about the best flushing two-piece toilets for a full comparison of two-piece options at this performance level.

The UltraMax II delivers the same Double Cyclone performance and 1,000-gram MaP score as the Drake II inside a seamless one-piece body that eliminates the tank-to-bowl joint where sediment and mold accumulate on two-piece designs, making it the preferred HET choice for bathrooms where hygiene and visual cleanliness matter.

The UltraMax II uses the same Double Cyclone nozzle system as the Drake II, so the flush performance is functionally identical at 1.28 gallons and 1,000-gram MaP. The difference is the monocoque body, which curves from tank to base without a seam. Aggregated reviews highlight two practical benefits: the tank-to-bowl gasket that can leak or degrade on two-piece models simply does not exist, and there is no joint ledge where cleaning cloths get caught. The tradeoff is weight, at roughly 99 pounds the UltraMax II is significantly heavier than a typical two-piece, so installation usually requires two people.

TOTO offers the UltraMax II with CeFiONtect glaze. The ion-barrier surface reduces particle adhesion in the bowl and trapway, so the 1.28-gallon flush moves through a low-friction ceramic passage rather than relying on volume to compensate. Owners in areas with mineral-heavy water report that the CeFiONtect version maintains a cleaner bowl with less chemical cleaner over time, which is both a hygiene and a maintenance cost benefit.

The Aquia IV is the TOTO dual-flush HET that achieves 1,000 grams on MaP at 1.28 gallons for solid waste and drops to 0.8 gallons for liquid-only cycles, so households that use the light flush consistently will average well below 1.0 gallon per flush across a day, the most water-efficient path available in a WaterSense-certified gravity toilet.

TOTO redesigned the Aquia IV from the Aquia III with a stronger full-flush siphon, pushing the MaP score from around 600 grams on the older model to a full 1,000 grams at 1.28 gallons. That is a significant improvement because dual-flush HET toilets historically lagged behind single-flush designs on clearing power, and owners who found the partial flush inadequate would use the full flush for every cycle, eliminating the dual-flush water savings. The Aquia IV's 1,000-gram full-flush score removes that concern entirely.

The skirted design on the Aquia IV hides the trapway behind smooth ceramic walls, which simplifies cleaning but means the trapway itself is not user-visible for inspection. TOTO's published trapway dimensions are 2 1/8 inches in diameter, consistent with the Drake II. For a broader look at dual-flush efficiency in the HET range, see our comparison of the best dual flush toilets.

The Kohler Cimarron is the HET model that consistently earns the strongest owner satisfaction scores among value-positioned WaterSense toilets, combining a 1,000-gram MaP score at 1.28 gallons with Kohler's AquaPiston canister flush valve, which draws water into the trapway from all 360 degrees rather than from one side as with a standard flapper design.

Kohler's AquaPiston canister is the defining feature of the Cimarron's value case. A standard flapper valve lifts to one side, restricting water entry to a partial arc. The AquaPiston rises vertically and opens a full circumferential waterway, so the bowl fills faster with the same volume. In MaP testing the Cimarron consistently scores 1,000 grams at 1.28 gallons, a result that its retail positioning would not predict but its engineering explains.

The Cimarron comes in both elongated and round bowl configurations and in multiple heights, which makes it one of the most format-flexible value HET options. Kohler backs it with a one-year warranty on parts. Owner reviews note that the AquaPiston canister requires less frequent replacement than rubber flappers, which is a long-term maintenance saving on top of the water bill reduction. See also our breakdown of the best Kohler toilets for a deeper look at where the Cimarron sits in Kohler's line.

The American Standard Cadet 3 is the most affordable toilet in this guide to score 1,000 grams on independent MaP testing at 1.28 gallons, and its large-diameter PowerWash rim scrub keeps the bowl cleaner between flushes than most toilets at this price point.

American Standard built the Cadet 3's PowerWash system around a large siphonic trapway with a fully glazed 2 3/8-inch opening, which is wider than the TOTO Drake II's 2 1/8-inch passage. The wider trapway reduces the hydraulic resistance the siphon must overcome, which helps explain how the Cadet 3 achieves 1,000-gram MaP performance on 1.28 gallons through a relatively conventional gravity mechanism rather than TOTO's dual-nozzle cyclone system. Owner reviews across aggregated platforms show a low clog rate and consistent single-flush clearance over years of heavy use.

American Standard's EverClean surface treatment is available on select Cadet 3 configurations. EverClean is an antimicrobial glaze additive built into the vitreous china that inhibits bacterial and mold growth on the bowl surface, which is distinct from CeFiONtect's friction-reduction function. Neither coating is available on every Cadet 3 SKU, so buyers who want the antimicrobial surface should confirm the specific model number before purchasing. For a deeper dive on this toilet, see our American Standard Cadet 3 review.

The Kohler Highline Arc brings the AquaPiston canister valve and a 1,000-gram MaP score into a tall, narrow two-piece silhouette that fits period bathrooms where a modern elongated profile would look out of place, combining EPA WaterSense compliance with a traditional tank line and comfort height bowl.

The Highline Arc is Kohler's long-standing workhorse two-piece, updated with the AquaPiston canister that the brand introduced to address flapper-related leak rates on its older models. The canister design is sealed at the top and bottom, so it is less prone to seal deformation than a rubber flapper that rolls back against a seat with every flush. Aggregated owner reviews show a lower incidence of phantom running water reports on Highline Arc models compared with the flapper-based Highline Classic, which suggests the AquaPiston seal durability claim holds up in the field.

The Highline Arc is available in a condensed 17-inch comfort height and in Kohler's Cachet seat configuration for buyers who want an integrated seat with soft-close function. At 1.28 gallons and 1,000-gram MaP it qualifies for WaterSense rebates in participating utility regions. Kohler's warranty coverage matches American Standard at one year for mechanical parts, with the ceramic body warranted against manufacturing defects for the life of the original owner.

The Woodbridge T-0001 is a one-piece elongated toilet with a fully skirted base, a soft-close seat, a dual-flush button on the tank top, and EPA WaterSense certification at 1.28 gallons, delivering a clean contemporary profile at a price well below comparable skirted models from TOTO or Kohler.

Woodbridge produces the T-0001 in vitreous china with a 3-inch flush valve, which is larger than the 2-inch or 2.5-inch valves common on lower-priced gravity toilets and contributes to the stronger-than-expected flush for a gravity siphon at 1.28 gallons. The dual-flush top button is set flush with the tank lid, giving the toilet a clean, uninterrupted horizontal surface from the rear rather than a protruding push lever. Owner reviews praise the aesthetic fit in modern bathrooms and note that the included soft-close seat adds meaningful value at the purchase price.

The skirted trapway on the T-0001 hides the contoured ceramic waste passage behind a smooth vertical wall, which makes floor cleaning significantly easier than on exposed-trapway designs. The tradeoff is that the skirted exterior adds to the overall ceramic mass, so at approximately 117 pounds the T-0001 is heavy for a two-person installation. Woodbridge's warranty is one year on parts. For a full comparison of one-piece options with skirted designs at various efficiency levels, see our guide to the best flushing one-piece toilets.

The American Standard Champion 4 carries WaterSense certification at 1.28 gallons per flush and is built around the widest glazed trapway in its class at 4 inches in bowl and 2 3/8 inches through the trap, specifically targeting households with high flush volumes or histories of chronic clogging on older large-waste toilets.

American Standard replaced the Champion 4's flapper with a 4-inch tower valve in later production runs, addressing the seal degradation issues that some earlier owners reported. The tower valve opens the full 4-inch bowl drain simultaneously and releases water with an initial surge that fills the siphon column faster than a standard 2-inch flapper, which is the primary reason the Champion 4 achieves its 1,000-gram MaP score at 1.28 gallons without requiring dual nozzle jets. The 2 3/8-inch fully glazed trapway then moves the waste column through with minimal friction.

Owners in households with five or more users report the lowest per-person clog incidence of any gravity HET toilet in this guide, based on aggregated review data. The Champion 4's EverClean surface is available on most current SKUs, adding antimicrobial protection to the bowl and reducing the frequency of cleaning required to maintain a hygienic surface under heavy daily use. Buyers replacing older 3.5 or 5-gallon Champion models will find the 1.28-gallon figure roughly one-third the volume they are used to, with equivalent or better single-flush clearance.

The Gerber Viper is the HET toilet that plumbers and building contractors reach for when they need WaterSense compliance, a proven clog-resistant flush, and parts that are available at supply houses rather than only online, making it the most maintenance-friendly choice in this guide for commercial light-duty or rental property applications.

Gerber's Viper uses an EcoFlush mechanism built around a tower-style flush valve with a sealed top rather than a flapper. The sealed tower design means water enters the flush column from all sides simultaneously, matching the AquaPiston geometry that Kohler uses. The trapway is fully glazed at 2 1/8 inches, consistent with TOTO's specification, and Gerber publishes the MaP score at 800 grams, which is the lowest in this guide but still well above the 350-gram residential threshold that confirms adequate single-flush clearance for normal household waste loads.

The Viper's main commercial advantage is parts sourcing. Gerber distributes through plumbing supply houses across the United States, so replacement flush valves, fill valves, seals, and lever assemblies are available same-day from a trade counter rather than on a 3-to-7 business day shipping window. For property managers running multiple units, that distribution network reduces toilet downtime to hours rather than days when a repair is needed. Gerber backs the Viper with a 10-year warranty on the china and a 5-year warranty on mechanical parts, which is stronger coverage than most consumer-positioned toilets in this guide.