MaP Flush Score Guide: What It Is and Why It Matters

Toilet manufacturers print phrases like "powerful flush," "clog-free technology" and "maximum performance" on boxes and product pages without any obligation to back those claims with external data. The MaP (Maximum Performance) testing program exists to replace that marketing language with a single, comparable number derived from the same controlled laboratory protocol applied identically to every toilet that submits for testing -- whether it sells for $150 or $1,500.

Understanding MaP scores does not require a plumbing background. It requires knowing what the test measures, how the score tiers map to real-world performance, and how to cross-reference that number against the water-use rating (GPF) and EPA WaterSense certification status of any toilet you are considering. Those three data points together give you more reliable purchase intelligence than any showroom demo or box copy ever could. For the shortlist of models that score highest across all three measures, see our roundup of the best flushing toilets.

What Is MaP Flush Testing and How Does It Work?

The soybean-paste media used in MaP testing was selected after research into materials that closely replicate the viscosity and cohesion of human fecal matter without presenting biological hazards in a lab environment. The paste is precision-formed into measured balls of known weight and loaded into the toilet bowl. The flush is triggered once, and lab engineers document what clears the trap in that single flush cycle. The process is repeated multiple times per model to account for any variation between flushes, and the published score reflects the maximum grams the toilet consistently clears across those repeated test runs.

It is important to understand what MaP does not test. The program evaluates bowl-clearance performance -- whether waste exits the bowl and passes through the trapway. It does not test downstream drain-line performance. A toilet with a 1000-gram MaP score can still experience issues if the home's horizontal drain run is partially blocked, undersized, or has poor slope. For bowl-level clogging, which is where the overwhelming majority of residential toilet clogs originate, MaP scores are the most objective performance indicator available to consumers purchasing without lab access.

What Is a Good MaP Score for a Toilet?

How Does MaP Score Relate to Gallons Per Flush (GPF)?

The federal maximum for new residential toilet installations in the United States was set at 1.6 gallons per flush by federal law in 1992. Before that law, many toilets used 3.5 gallons or more per flush, relying on sheer water volume to move waste. Modern low-flow toilets achieve equal or better performance through engineering: optimizing the angle of the trapway, increasing the diameter of the flush valve, shaping the rim wash pattern, and designing bowl geometry that accelerates siphon formation.

The practical consequence for buyers is that more water does not guarantee more flushing power. A mid-grade 1.6 GPF toilet from a decade ago might score 450 grams on MaP. A TOTO Drake at 1.28 GPF scores 1000 grams. The engineering quality of the bowl, not the volume of water delivered per flush, is what determines performance. To understand how water efficiency and flush power interact across different toilet types, our complete toilet buying guide covers each specification in detail alongside how they relate to one another.

Which Toilet Has the Strongest Flush?

What Is the Best Toilet for Preventing Clogs?

Which Toilet Offers the Best Value per MaP Score Point?

MaP Score by Brand: How TOTO, Kohler, American Standard, Gerber, Woodbridge and Swiss Madison Compare

Not all brands approach MaP performance the same way, and the patterns across the major players reveal engineering priorities that the marketing names obscure. Here is how each brand's lineup maps to MaP scores across their primary residential models.

TOTO

TOTO's residential lineup is the most consistent performer in the MaP database across its full price range. The Drake (G-Max) earns 1000 grams at 1.28 GPF -- the gold standard combination. The Drake II (Double Cyclone) earns up to 1000 grams at 1.28 GPF and adds a quieter flush mechanism. The UltraMax II (Tornado Flush) earns approximately 800 grams at 1.28 GPF, with the score tradeoff offset by its rimless bowl design that delivers superior rim coverage with every flush. The Aquia IV is TOTO's dual-flush line, earning around 800 grams on its 1.28 GPF full-flush cycle. The Entrada, TOTO's entry-level model, earns scores in the 600-gram range -- respectable at its price tier but below TOTO's flagship performance. The Vespin II, a skirted two-piece design with a concealed trapway, earns scores around 800 to 1000 grams depending on configuration. TOTO's CeFiONtect glaze, available on many models as an upgrade, creates an ion-barrier ceramic surface that reduces waste and mineral adhesion -- a feature the MaP score does not capture but aggregated owner reviews consistently praise in hard-water households.

Kohler

Kohler's primary flush mechanism is the AquaPiston canister, a full-diameter canister that opens 360 degrees around its circumference rather than lifting like a traditional flapper. Kohler claims this delivers 90 percent greater water contact area during the initial flush burst. The Cimarron with AquaPiston earns up to 1000 grams in some configurations at 1.28 GPF, making it the closest Kohler equivalent to the TOTO Drake on pure MaP performance. The Highline earns scores in the 600 to 800-gram range depending on SKU. The Santa Rosa one-piece earns around 800 grams. The Memoirs earns comparable scores to the Highline. Kohler offers a limited lifetime warranty on the AquaPiston flush mechanism on the Cimarron, which is one of the stronger component warranties among major brands at this price tier.

American Standard

American Standard's Champion 4 name refers to its 4-inch diameter flush valve -- the largest in the standard residential class -- which enables the toilet to dump its full 1.6-gallon tank into the bowl in a near-instantaneous burst. The result is a 1000-gram MaP score and a 2-3/8-inch trapway, the widest in the residential gravity category. The tradeoff is that the Champion 4 uses 1.6 GPF, so it does not qualify for WaterSense certification. The Cadet 3 earns scores in the 600 to 800-gram range at 1.28 GPF with WaterSense certification, making it American Standard's value entry in the efficiency-focused bracket. American Standard offers a limited lifetime warranty on the Champion 4, covering the porcelain and working parts.

Gerber

Gerber is one of the most underrepresented brands in consumer awareness despite consistently strong MaP scores relative to price. The Viper earns an 800-gram MaP score at 1.28 GPF with WaterSense certification. The Avalanche earns similar scores and adds ADA-compliant comfort height as a standard feature. Gerber's CleanCurve rim design reduces the horizontal ledge under the bowl rim where bacteria typically accumulate, improving hygiene without requiring a fully rimless bowl redesign. Plumbers who install dozens of toilets per year frequently cite Gerber by name as a reliable, low-return-service brand, which is a form of field validation that consumer marketing cannot replicate.

Woodbridge

Woodbridge has grown market share by offering skirted one-piece designs at prices that undercut Swiss Madison and TOTO one-piece models. The T-0001 and T-0019 carry reported MaP scores around 800 grams at 1.28 GPF with WaterSense certification. The skirted exterior conceals the trapway behind a smooth base for easier exterior cleaning. Woodbridge's replacement-parts ecosystem is smaller and less established than TOTO, Kohler or American Standard, which is worth factoring into long-term maintenance planning. For a detailed comparison of how one-piece skirted designs differ from conventional exposed-trapway two-piece toilets, see our guide on one-piece vs two-piece toilets.

Swiss Madison

Swiss Madison focuses on wall-hung and floor-mounted designs with modern European aesthetics. The St. Tropez is the flagship model in its floor-mounted line, using a dual-flush 0.8/1.28 GPF mechanism with WaterSense certification. MaP scores for Swiss Madison models depend partly on the in-wall carrier system used with wall-hung configurations, making direct comparison harder than for floor-mount toilets. For floor-mounted St. Tropez installations, scores are generally in the 600 to 800-gram range. The modern skirted profile and dual-flush controls appeal to design-forward buyers, though the flush scores do not match the TOTO Drake or American Standard Champion 4 at the performance ceiling.

MaP Score vs. Manufacturer Flush System Names: What the Numbers Actually Tell You

Every major toilet brand markets its flush technology under a proprietary name. TOTO uses G-Max, Double Cyclone, and Tornado Flush depending on the model series. Kohler uses AquaPiston and Revolution 360. American Standard uses Champion, ActiClean, and Right Height. Gerber uses CleanCurve and HET. These names describe genuine engineering differences -- the mechanism of water delivery into the bowl, the geometry of the rim wash, the valve opening size -- but they are not standardized across brands and do not produce a number you can compare from one manufacturer to another.

The MaP score translates all of those proprietary systems into a single, externally verified number using the same test. A G-Max flush and an AquaPiston flush compete on equal terms in the MaP lab. When a toilet has a bold proprietary flush name but a weak or absent MaP score, the flush name tells you nothing about actual performance. When a toilet earns a specific MaP gram rating, that rating tells you exactly what the technology achieved under the same conditions applied to every other submitted model.

There are features that MaP does not measure, and it is worth knowing them. The test measures bulk solid-waste clearance. It does not formally measure how thoroughly the rim wash rinses the bowl interior on each flush, how quiet the flush is, how quickly the bowl refills, or how well the bowl surface resists staining between cleanings. TOTO's CeFiONtect ceramic glaze and the rimless Tornado Flush design both deliver real advantages in bowl hygiene that a 1000-gram MaP score does not capture. For a comprehensive view of how flush mechanisms affect both performance and cleaning, see our complete toilet selection guide.

How to Look Up a MaP Score Before You Buy

The MaP database is publicly accessible at map-testing.com at no cost. You can search by manufacturer name, product series name, or model catalog number. The database shows the MaP score alongside the specific flush volume tested, which is important because the same product family sometimes includes both 1.28 GPF and 1.6 GPF variants with different MaP scores. Always confirm you are looking at the MaP score for the GPF version you intend to purchase.

Using catalog numbers rather than marketing names

Marketing names are not unique in the MaP database. Searching for "Drake" will return multiple results. For accuracy, use the manufacturer's catalog number. TOTO lists the Drake under catalog numbers like CST744E (elongated, 1.28 GPF) or CST743E (the 1.6 GPF version, which carries a different score). Kohler's Cimarron appears under K-3609 and K-3887 depending on configuration. American Standard's Champion 4 is listed as 2034.014 (round) and 2021.014 (elongated). If you find the toilet you are considering on a retailer's site, the product detail page or spec sheet should list the manufacturer catalog number, and that is the search term to use in the MaP database.

Retailer-exclusive model numbers

Large home improvement retailers often carry toilets under store-exclusive model numbers that are manufactured by the same brands but carry different SKUs. In those cases, the MaP database may not list the retailer SKU directly. The approach is to identify the base model the retailer SKU corresponds to -- often listed in the product's specification sheet as the "equivalent" or "base" model -- and look up that number instead. If no connection to a listed model can be established and the retailer provides no MaP documentation, that is a signal to consider a model with publicly verifiable data instead.

How MaP Scores Interact with Trapway Design

The MaP score measures what exits the bowl in a single flush, but the trapway -- the S-shaped passage through which waste exits the bowl into the drain line -- is the mechanical link between a high score and real-world clog resistance. A high MaP score without a wide, fully glazed trapway can still produce occasional clogs when waste volume is large or drain conditions are marginal.

Trapway diameter and glazing

Standard residential trapways measure 2 inches in diameter. The TOTO Drake uses a 2-1/8-inch fully glazed trapway -- the extra eighth of an inch reduces friction and lowers the probability of a solid lodging in transit. The American Standard Champion 4 uses a 2-3/8-inch fully glazed trapway, the widest in the standard residential category. Fully glazed means the interior surface of the trapway is coated with the same ceramic glaze as the bowl, which reduces the friction coefficient and makes waste transit smoother versus an unglazed concrete-finish interior.

Skirted vs exposed trapways

Skirted toilets like the Woodbridge T-0001, TOTO Vespin II and Swiss Madison St. Tropez conceal the trapway behind a smooth flat base panel. The skirted exterior makes cleaning the outside of the toilet far easier -- no S-curve ceramic surface to scrub -- but uses the same internal trapway engineering as exposed designs. A skirted toilet with an 800-gram MaP score is not structurally different in flush performance from an exposed-trapway toilet with the same score. The difference is purely exterior. For guidance on choosing between skirted and exposed designs based on cleaning, installation and budget, see our guide on one-piece versus two-piece toilet designs.

MaP Score and EPA WaterSense: How the Two Certifications Work Together

EPA WaterSense is a voluntary certification program managed by the U.S. Environmental Protection Agency. To earn WaterSense certification, a toilet must use 1.28 gallons per flush or less and pass a minimum flush performance standard established by the program's protocols. Critically, WaterSense's performance standard is not the same as MaP testing. WaterSense verifies that the toilet can flush an adequate amount of waste, but the threshold it uses is significantly lower than the MaP program's performance ceiling. A toilet can carry a WaterSense label and still earn only a 500-gram MaP score.

The practical implication is that WaterSense certification alone does not guarantee strong flush performance. It guarantees that the toilet uses 1.28 GPF or less and passes a minimum adequacy threshold. For a buyer choosing between two WaterSense-certified toilets, the MaP score is still the variable that determines which one will actually outperform the other on a family bathroom's daily demands. The combination of WaterSense certification plus a MaP score of 800 grams or higher is the complete specification target: it confirms both water efficiency and verified flush power at the level the program was designed to validate.

Many municipalities and water utilities in the United States and Canada offer rebates for installing EPA WaterSense-certified toilets. These rebates can range from $25 to $200 depending on the program and the local utility. Replacing a pre-1994 toilet (which may have used 3.5 to 7 gallons per flush) with a WaterSense-certified 1.28 GPF model saves approximately 13,000 gallons of water per year in a household of four. That volume reduction is the driver behind utility rebate programs, and it makes the WaterSense certification financially meaningful beyond its labeling function. For more context on water efficiency across toilet types, our guide on round versus elongated toilet selection includes water use considerations by bowl type.

Top MaP-Rated Toilet Picks by Use Case

Based on published MaP scores, WaterSense status, trapway design, and aggregated owner review patterns, three toilets stand out as the clearest recommendations for distinct buyer situations.

How to Use MaP Scores in a Complete Buying Decision

MaP score is the most important single data point in a toilet purchase, but it does not operate in isolation. A toilet that scores 1000 grams but does not fit your bathroom's plumbing is useless. Here is how MaP data integrates with the rest of the purchase specification.

Establish your MaP floor first

Before comparing models, set a minimum acceptable MaP score based on your bathroom's use pattern. A guest bath used occasionally by one or two people can function acceptably at 600 grams. A master bathroom used by a family of four every morning should start at 800 grams and go to 1000 grams if there is any history of clogging. Setting the floor first eliminates a significant portion of the market from consideration without requiring detailed comparison.

Confirm rough-in before anything else

Rough-in is the distance from the finished back wall to the center of the floor drain. The standard is 12 inches, and the overwhelming majority of toilets are built for it. Homes built before 1970, and some tight layout renovations, use 10-inch rough-ins. A toilet purchased for a 12-inch rough-in will not seat against the wall in a 10-inch rough-in bathroom. Measure before you filter by MaP score. Our toilet buying guide includes a step-by-step rough-in measurement walkthrough alongside every other dimension that determines fit.

Match GPF to your water situation

If your municipality offers rebates for WaterSense toilets, buying a 1.28 GPF model reduces net purchase cost and lowers ongoing water bills. If your home has a septic system, confirm with the system installer whether high-volume flushes at 1.6 GPF or lower-volume 1.28 GPF flushes are better for your specific tank and field configuration. Most modern septic systems handle 1.28 GPF well, but the question is worth asking if the system is older or undersized.

Choose bowl shape for your floor space

Elongated bowls project 28 to 31 inches from the wall and add approximately 2 inches of front-to-back length compared to round bowls. In a bathroom with 30 or more inches of clear space in front of the toilet, elongated is the more comfortable choice for adult users. In compact bathrooms where clearance to the door or vanity is tight, a round bowl recovers those 2 inches without affecting flush performance. MaP scores for round and elongated versions of the same model can differ slightly -- manufacturers sometimes publish separate scores by bowl shape. Check the score for the specific bowl shape you intend to buy. For a detailed comparison of both options, see our guide on round versus elongated toilets.

Factor in one-piece versus two-piece

One-piece toilets have no seam between the tank and bowl, which simplifies exterior cleaning and gives a more modern visual profile. Two-piece toilets are lighter during installation (the tank and bowl ship and install separately), cheaper to purchase, and easier to repair since individual components can be replaced without sourcing the complete toilet unit. Flush performance across one-piece and two-piece designs at equivalent MaP scores is functionally the same. The decision reduces to cleaning preference, budget, and bathroom aesthetic. Bowl shape comparisons across both configurations are covered in detail in our guide on one-piece versus two-piece toilets.

Common questions answered

Frequently Asked Questions

? What does MaP stand for in the context of toilets?

MaP stands for Maximum Performance. It is the name of an independent third-party flush testing program developed with input from water utility agencies in the United States and Canada. The program measures how many grams of solid waste a toilet clears in a single flush and publishes results publicly at map-testing.com so consumers and plumbers can compare any listed model on equal terms.

? What is a good MaP score for a toilet?

A MaP score of 800 grams or higher is excellent for a busy household bathroom, and 1000 grams is the maximum the program awards. Scores of 600 to 799 grams are good for lighter-use bathrooms. For a family of three or more adults, target 800 grams as the minimum and prefer 1000 grams if there is any history of clogging in the household.

? What is the maximum MaP score a toilet can receive?

The maximum MaP score awarded by the program is 1000 grams. Several widely available residential toilets achieve this ceiling, including the TOTO Drake (G-Max, 1.28 GPF), the American Standard Champion 4 (1.6 GPF), and some configurations of the Kohler Cimarron (AquaPiston, 1.28 GPF).

? How does MaP testing actually work?

Certified labs use a standardized soybean-paste media -- formulated to approximate the density and cohesion of human waste -- shaped into balls of precise measured weight. The balls are placed in the toilet bowl and the toilet is flushed once. Engineers document what clears the trap in that single flush. The test is repeated multiple times per model and the final score is the maximum grams consistently cleared across those runs.

? Is a higher MaP score always better?

Higher is better in terms of flush power and clog resistance. However, a household with light use and no clogging history does not necessarily need a 1000-gram toilet to function well. An 800-gram score covers most residential situations comfortably. The 1000-gram ceiling is the recommendation for households with heavy use, large waste volumes, or older drain lines where clearance power matters most.

? Can I look up a specific toilet's MaP score before buying?

Yes. The MaP database is publicly available at map-testing.com at no cost. Search by manufacturer name, model series name, or manufacturer catalog number. The database shows the MaP score alongside the specific flush volume (GPF) tested for that entry, so you can confirm the score corresponds to the exact configuration you plan to purchase.

? Does a higher GPF always mean a higher MaP score?

No. Water volume and MaP score are independent. A well-engineered 1.28 GPF toilet can outperform a poorly designed 1.6 GPF toilet by hundreds of MaP grams. The TOTO Drake earns 1000 grams at 1.28 GPF while some 1.6 GPF models score well below 800 grams. Bowl geometry, flush valve diameter, trapway design, and water delivery velocity all influence MaP scores more directly than raw gallon volume.

? Does MaP testing require the manufacturer to pay?

Manufacturers pay a submission fee to enter the MaP program, but the testing is conducted by independent certified laboratories using a standardized protocol that does not allow manufacturers to influence the result. The protocol is identical for every submitted model regardless of brand or price tier, and results are published publicly whether the score is strong or weak. The fee covers lab time; it does not buy a favorable result.

? What is the MaP score for the TOTO Drake?

The TOTO Drake with G-Max flush at 1.28 GPF earns a 1000-gram MaP score -- the maximum the program awards. This makes it the benchmark for gravity-flush residential performance because it achieves the MaP ceiling while using 20 percent less water than the federal 1.6-gallon maximum and carrying EPA WaterSense certification.

? Does EPA WaterSense certification require a strong MaP score?

No. EPA WaterSense certification requires that a toilet use 1.28 GPF or less and pass WaterSense's own minimum performance protocol, which is a lower threshold than the MaP program's scoring range. A toilet can carry WaterSense certification with a relatively modest MaP score. WaterSense verifies water efficiency; MaP verifies flush power. A strong toilet satisfies both, but they are separate programs with separate standards.

? What MaP score does the American Standard Champion 4 have?

The American Standard Champion 4 earns a 1000-gram MaP score -- the maximum -- but at 1.6 GPF rather than 1.28 GPF. It uses a 4-inch wide flush valve (the largest in the standard residential class) and a 2-3/8-inch fully glazed trapway. The tradeoff compared to the TOTO Drake is 25 percent more water per flush in exchange for the same maximum MaP score and the widest trapway available in this category.

? Do round and elongated bowl versions of the same toilet have different MaP scores?

Yes, scores can vary by bowl shape within the same product family. The elongated bowl's different interior geometry affects how the flush siphon forms and how waste interacts with the flush stream. Manufacturers often publish separate MaP scores for round and elongated versions. Always confirm the score for the exact bowl shape you plan to purchase, not just the product family average.

? What MaP score does the Gerber Viper earn?

The Gerber Viper earns a documented MaP score of approximately 800 grams at 1.28 GPF with EPA WaterSense certification. For the specific model number you intend to purchase, confirm the current published score at map-testing.com, as scores can vary slightly between production runs and SKU variants within the same product family.

? How does the MaP score for a dual-flush toilet work?

Dual-flush toilets have two flush volumes -- typically 0.8 GPF for liquids and 1.28 GPF for solids. MaP testing for dual-flush models is conducted at the full-flush setting (1.28 GPF), because that is the cycle used for solid waste clearance. The partial flush is not MaP-scored for solid performance since it is designed for liquid waste only. When evaluating a dual-flush toilet on MaP, confirm the score comes from the full-flush cycle.

? Does MaP testing cover toilet paper clearance?

The primary MaP protocol uses soybean-paste media to test solid waste clearance. The program has expanded certain test protocols to include optional paper-clearance assessments, but the widely published MaP gram score specifically refers to the solid-waste clearance test. A high MaP score is a strong indicator of overall flush power, and toilets that clear 1000 grams of solid media typically handle paper clearance without issue, but the score itself does not formally certify paper performance.

? Do all toilet brands submit their products for MaP testing?

No. MaP testing is voluntary. Major brands including TOTO, Kohler, American Standard and Gerber routinely submit their primary residential lines. Some smaller or newer brands do not participate, which means no publicly verifiable third-party performance score exists for those models. When a toilet you are considering has no MaP listing, that absence is meaningful information and warrants consideration before purchasing based solely on manufacturer claims.

? Does the TOTO Aquia IV have a MaP score?

The TOTO Aquia IV is a dual-flush toilet (0.9 GPF / 1.28 GPF) with WaterSense certification. MaP testing on the full-flush cycle places the Aquia IV in the 800-gram range depending on configuration. The Aquia IV sacrifices some flush aggressiveness compared to the single-flush Drake in exchange for a lower full-flush water volume and the added flexibility of the partial-flush option for liquid-only waste.

? Is a 500-gram MaP score too low for a family bathroom?

For a bathroom used regularly by two or more adults, a 500-gram MaP score is at the lower boundary of acceptable performance. At 500 grams, the toilet will handle light-to-moderate waste volumes without clogging, but heavy-use scenarios or above-average waste volumes are likely to result in occasional double-flushing or clogs. For family bathrooms, target 800 grams as the practical minimum to provide a meaningful margin against real-world use variation.

? What does a fully glazed trapway mean and why does it matter?

A fully glazed trapway means the interior surface of the waste passage through the ceramic body of the toilet is coated with the same ceramic glaze as the bowl interior. Glazing reduces the friction coefficient of the surface, which allows waste to slide through more smoothly and reduces the adhesion points where solid waste could lodge. An unglazed trapway has a rougher concrete-like interior that increases friction and clogging risk. All else being equal, a fully glazed trapway contributes to clog resistance beyond what the MaP score alone documents.

? How often is the MaP database updated?

The MaP database at map-testing.com is updated periodically as manufacturers submit new models and as existing models are re-tested when production specifications change. It is not updated in real time, so there can be a lag between a product launch and its appearance in the database. If you are evaluating a newly released toilet that is not yet listed, the absence of a MaP score may reflect timing rather than a decision not to submit -- but in that case, waiting for the listing before purchasing is the lower-risk approach.

Sources

• EPA WaterSense, epa.gov/watersense
• MaP (Maximum Performance) flush testing, map-testing.com
• Manufacturer published specifications (TOTO, Kohler, American Standard)