Toilet Flush Test Results: MaP Scores All Top Models

The TOTO Drake II earns its position at the top of every serious MaP ranking: a verified 1,000-gram score at just 1.28 GPF, backed by TOTO's E-Max flushing system and the brand's industry-leading CeFiONtect glaze that resists staining and reduces cleaning frequency.

The Drake II uses TOTO's E-Max flush system, which combines a 3-inch flush valve, a fully glazed 2-1/8-inch trapway, and a large water surface area to generate siphonic action reliably. Owner reviews consistently describe years of clog-free use even in households with children or guests who flush non-standard items.

At 1.28 GPF, the Drake II saves approximately 20 percent water versus older 1.6 GPF models while matching or exceeding their flushing performance. For anyone replacing a pre-1994 toilet running at 3.5 to 5 GPF, the water bill impact is significant. See our full comparison in the TOTO Drake II review.

The UltraMax II delivers the same 1,000-gram MaP score and E-Max flush system as the Drake II but in a seamless one-piece design that eliminates the tank-to-bowl joint -- the single most common source of toilet leaks over time.

The UltraMax II's flush system is mechanically identical to the Drake II -- same 3-inch flush valve, same fully glazed trapway, same E-Max siphonic action. The performance difference between the two is essentially zero in real-world use. The choice comes down to aesthetics, ease of cleaning, and budget.

One-piece toilets have fewer seams for bacteria and mildew to colonize, which is why they are common in commercial settings and master bathrooms where appearance matters. The UltraMax II's SoftClose seat (included on some SKUs) also adds a premium touch that aggregated owners frequently cite in positive reviews.

The TOTO Aquia IV hits the rare trifecta: 1,000-gram MaP on its full flush, EPA WaterSense certification, and TOTO's Double Cyclone flush system that cleans the bowl with two nozzles instead of rim holes -- a design that resists mineral buildup in hard water areas.

The Aquia IV's Double Cyclone system is a notable departure from the rim-hole design used by most toilets. Two nozzles create a centrifugal washing action that covers more bowl surface area than a standard rim wash. In hard water regions where mineral deposits clog rim holes over time, this is a practical long-term advantage.

Households in California, Colorado, and other water-restricted states can often claim utility rebates for WaterSense-certified dual-flush toilets. The Aquia IV's average GPF across typical use (assuming roughly a 60/40 split between partial and full flushes) works out to approximately 1.1 GPF -- a genuine efficiency gain over single-flush 1.28 GPF models.

The Champion 4 holds the record for the largest flush valve (4-inch) in the consumer market, and its 2-3/8-inch fully glazed trapway -- the widest in its category -- is the primary reason it reaches 1,000 grams on MaP testing despite using a relatively straightforward gravity-feed mechanism.

The Champion 4 was designed specifically to address the chronic clogging complaints that plagued early low-flow toilets in the 1990s and 2000s. American Standard's answer was to make the trapway and flush valve physically larger so water moves faster and waste clears more reliably. It worked: the Champion 4 has one of the longest clog-free track records among consumer toilets sold in North America.

The trade-off is water use. At 1.6 GPF, the Champion 4 uses 25 percent more water per flush than a WaterSense-certified 1.28 GPF model. For most households that is a manageable cost, but in drought-restricted states or for households paying high utility rates, the difference adds up over years of use. See how it stacks up in our head-to-head Champion 4 vs Drake II comparison.

The American Standard Cadet 3 delivers a verified 1,000-gram MaP score and EPA WaterSense certification at a price point that typically undercuts the TOTO Drake II -- making it one of the most compelling value propositions in the high-performance toilet category.

The Cadet 3 uses American Standard's Cadet 3 PowerWash rim, which directs water from beneath the rim to scour the bowl surface during each flush. Combined with the EverClean antimicrobial surface, owner reviews indicate satisfactory cleaning performance with less frequent manual scrubbing than older American Standard designs.

For apartment renovations, rental properties, or guest bathrooms where top-tier aesthetics are less critical, the Cadet 3 delivers the flushing performance that matters most -- 1,000 grams cleared reliably -- at an accessible price point. Compare both American Standard workhorses in the detailed Champion 4 vs Cadet 3 breakdown.

The Kohler Cimarron reaches 1,000 grams on MaP testing using Kohler's AquaPiston canister flush valve, which opens a 360-degree water path instead of the hinged-flapper approach -- a design that reduces the mechanical parts most likely to wear out and cause running or incomplete flushes.

Kohler's AquaPiston canister valve is the core differentiator of the Cimarron. Instead of a traditional rubber flapper that opens on one side, the canister lifts vertically, allowing water to flow from all directions simultaneously. The result is a faster, more uniform water release that generates reliable siphonic action at 1.28 GPF.

The Cimarron's comfort-height bowl (roughly 17 to 17.5 inches to the top of the seat) makes it a good fit for households with older adults or anyone who finds standard-height toilets (about 15 inches) uncomfortable. This is worth checking in the full Kohler Cimarron review.

The Woodbridge T-0001 is a one-piece concealed-trapway toilet with a 800-gram MaP score at 1.28/0.8 GPF dual flush, making it the most aesthetically contemporary option on this list at a price point well below the TOTO or Kohler models -- a reasonable trade-off for secondary bathrooms.

The T-0001's 800-gram MaP score is solidly above the 600-gram threshold where double-flushing becomes a recurring annoyance. For a two-person household or a guest bathroom with light use, 800 grams is more than sufficient. The concealed skirted trapway and the included soft-close seat are features that typically cost extra on comparable models from TOTO and Kohler.

The main caveat for Woodbridge is long-term parts availability. TOTO and Kohler have deep domestic distribution networks; Woodbridge parts may require ordering directly from the manufacturer. For a primary bathroom in a family home, that matters. For a guest bath used occasionally, it rarely comes up.