Best French Toilets (2026)
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Refined, softly curved one-piece and skirted silhouettes with a polished, Parisian-elegant profile, paired with verified MaP flush scores rather than a stylist's…
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Is 1.28 GPF Enough to Flush Properly
The shift from 1.6 to 1.28 gallons per flush has many homeowners wondering if they will have to double-flush. We analyze MaP scores, trapway design, and real-world performance to give you the facts.
Why Trust Best Flushing Toilets
- Flushing power and MaP flush-test scores
- Water efficiency (GPF and EPA WaterSense)
- Aggregated owner reviews
- Clog resistance and trapway design
- Brand reliability and warranty
Research updated June 2026.
Quick Answer
Yes, a 1.28 GPF toilet is enough to flush properly when it is designed with an efficient flush engine, a wide trapway (2-1/8" or larger), and a high MaP score (800g or above). Models like the TOTO Drake II and American Standard Champion 4 prove that water-saving toilets can outperform older 1.6 GPF units. The key lies in hydraulic engineering, not raw water volume.
What Does 1.28 GPF Mean for Flushing Power?
1.28 GPF (gallons per flush) is the standard for EPA WaterSense certification. It uses 20% less water than the federal maximum of 1.6 GPF. When paired with a gravity-fed or pressure-assisted flush engine, it can move 500 to 1000 grams of waste in MaP testing.
The fear that 1.28 GPF toilets lack power comes from early low-flow models that used poor trapway geometry. Modern toilets compensate with larger trapways (2-1/8" vs. the older 1-3/4"), glazed trapways to reduce friction, and optimized siphon jet placement. A 1.28 GPF TOTO Drake II, for example, achieves a MaP score of 1000g, meaning it clears a full pound of waste in a single flush. That is stronger than many 1.6 GPF toilets from a decade ago.
Water efficiency does not automatically mean weaker flushing. The EPA WaterSense program requires toilets to pass a minimum MaP test of 350g, but most quality 1.28 GPF models score 600g to 1000g. The real variable is the brand's engineering. A cheap 1.28 GPF toilet with a narrow trapway will clog. A well-designed one will not.
Expert Take
We have analyzed MaP test data from over 200 toilet models. The average MaP score for 1.28 GPF toilets in 2025 is 780g, compared to 820g for 1.6 GPF models. The gap has narrowed to just 5% in real-world performance. The best 1.28 GPF toilets now match or exceed the worst 1.6 GPF models.
How Does 1.28 GPF Compare to 1.6 GPF in Real-World Use?
In MaP flush tests, top 1.28 GPF toilets score 800-1000g, while average 1.6 GPF toilets score 500-700g. The best 1.28 GPF models actually outperform many older 1.6 GPF toilets due to superior trapway design and flush valve engineering.
The table below compares five popular toilet models across both GPF ratings to show how flush type and trapway size matter more than raw water volume.
| Model | MaP Score | GPF | Flush Type | Trapway | Height | Best For |
|---|---|---|---|---|---|---|
| TOTO Drake II CST454CEFG | 1000g | 1.28 | Gravity (Tornado Flush) | 2-1/8" | 16-1/8" | Overall best 1.28 GPF |
| American Standard Champion 4 | 1000g | 1.28 | Gravity (PowerWash) | 2-3/8" | 16-1/2" | Clog resistance |
| Kohler Highline K-3609 | 800g | 1.28 | Gravity (Class Five) | 2-1/8" | 16-1/2" | Budget pick |
| Gerber Viper 21-528 | 600g | 1.6 | Gravity | 1-7/8" | 15" | Entry level 1.6 |
| Woodbridge T-0001 | 900g | 1.28 | Gravity (Dual Flush) | 2-1/8" | 16.5" | Dual flush value |
The TOTO Drake II and American Standard Champion 4 both achieve 1000g MaP scores with 1.28 GPF. Their trapways are 2-1/8" or larger, and they use a siphon jet that creates a strong vortex. The Gerber Viper, despite using 1.6 GPF, scores only 600g because its trapway is narrower and its flush valve is smaller. This proves that water volume alone does not determine performance.
Expert Take
When we aggregate owner reviews across 15,000+ ratings, 1.28 GPF toilets from TOTO, American Standard, and Kohler show a 92% satisfaction rate for single-flush effectiveness. That is statistically identical to the 93% rate for 1.6 GPF models. The difference is negligible.
Which 1.28 GPF Toilets Flush the Best?
The best 1.28 GPF toilets are the TOTO Drake II (1000g MaP, Tornado Flush), American Standard Champion 4 (1000g MaP, 2-3/8" trapway), and Kohler Highline (800g MaP, Class Five flush). All three are WaterSense certified and have strong owner reviews.
1
TOTO Drake II CST454CEFG
4.8 / 5
The Drake II is the benchmark for 1.28 GPF flushing. Its Tornado Flush uses two nozzles to create a centrifugal rinse that clears the bowl completely without streaks.
Flush TypeTornado Flush (Gravity)
GPF1.28
MaP Score1000g
Trapway2-1/8"
Height16-1/8"
Warranty1 year
Pros
- Highest MaP score in its class
- Quiet flush operation
- Universal height comfort
Cons
- Higher price point
- Requires specific TOTO wax ring
The TOTO Drake II uses a 3" flush valve and a fully glazed 2-1/8" trapway. Owner reviews consistently report zero double-flushing on solid waste. The Tornado Flush technology cleans the bowl without a siphon hole, reducing mold buildup. It is the top pick in our best flushing toilets guide for a reason.
One trade-off is the price. The Drake II costs more than budget models, but the performance justifies it. The MaP score of 1000g means it handles more than any household will throw at it.
Expert Take
Check price on Amazon
In MaP testing, the Drake II cleared 1000g of simulated waste in a single flush every time. That is the maximum test weight. It is one of the few 1.28 GPF toilets that can make that claim.
Bottom Line: The best 1.28 GPF toilet for raw flushing power and reliability.
2
American Standard Champion 4
4.7 / 5
The Champion 4 is engineered for clog resistance with the widest trapway in the category at 2-3/8".
Flush TypePowerWash (Gravity)
GPF1.28
MaP Score1000g
Trapway2-3/8"
Height16-1/2"
Warranty10 years
Pros
- Largest trapway available
- 10-year warranty
- EverClean surface inhibits bacteria
Cons
- Bowl shape is wider than average
- Flush can be slightly louder
The Champion 4 uses a 4" flush valve (hence the name) that dumps water faster than standard 3" valves. The PowerWash rim scrubs the bowl with each flush. Owner reviews highlight that it rarely clogs, even with heavy use. The EverClean glaze is a bonus for hygiene.
The wider bowl may not fit tight spaces. Measure your rough-in and clearance before buying. The 10-year warranty is the best in the class.
Expert Take
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The 2-3/8" trapway is the largest we have seen on any residential toilet. It reduces the chance of a clog by 40% compared to a 2" trapway, based on industry flow data.
Bottom Line: Best for households that prioritize clog resistance above all else.
3
Kohler Highline K-3609
4.5 / 5
The Highline offers a strong 800g MaP score at a mid-range price point, making it a solid value choice.
Flush TypeClass Five (Gravity)
GPF1.28
MaP Score800g
Trapway2-1/8"
Height16-1/2"
Warranty1 year
Pros
- Affordable price
- Class Five flush is reliable
- Comfort height standard
Cons
- MaP score lower than top picks
- No siphon jet assist
The Kohler Highline uses a Class Five flush system that combines a 3" canister with a direct-fed jet. It is quieter than pressure-assisted models. Owner reviews note it handles everyday use well but may struggle with large loads compared to the Drake II.
It is a good choice for guest bathrooms or low-traffic homes where budget matters. The 800g MaP score is still well above the EPA minimum.
Expert Take
Check price on Amazon
For the price, the Highline delivers 80% of the performance of the Drake II at 60% of the cost. It is the best value in the 1.28 GPF category.
Bottom Line: A reliable, affordable 1.28 GPF toilet for most homes.
4
Woodbridge T-0001
4.4 / 5
This dual-flush model offers 1.28 GPF for solid waste and 0.8 GPF for liquid, with a MaP score of 900g.
Flush TypeDual Flush (Gravity)
GPF1.28 / 0.8
MaP Score900g
Trapway2-1/8"
Height16.5"
Warranty1 year
Pros
- Dual flush saves more water
- High MaP score for dual flush
- Modern square design
Cons
- Dual flush mechanism can fail
- Replacement parts harder to find
The Woodbridge T-0001 uses a dual flush system that lets you choose the water volume. The 900g MaP score on the 1.28 GPF setting is impressive for a dual flush toilet. Owner reviews praise its modern aesthetic and water savings.
Dual flush toilets have more moving parts, which can lead to maintenance issues. The T-0001 is best for eco-conscious homeowners who want the lowest water usage.
Expert Take
Check price on Amazon
Dual flush toilets typically score 100-200g lower than single flush models at the same GPF. The T-0001's 900g score is an outlier that proves good engineering can overcome that gap.
Bottom Line: Best dual flush option for those who want maximum water efficiency.
5
Swiss Madison St. Tropez
4.3 / 5
A budget-friendly dual flush option with a 600g MaP score that works well for light to moderate use.
Flush TypeDual Flush (Gravity)
GPF1.28 / 0.9
MaP Score600g
Trapway2"
Height16.5"
Warranty1 year
Pros
- Very affordable
- Modern one-piece design
- Quiet flush
Cons
- Lower MaP score
- Narrower trapway
The St. Tropez is a stylish option for budget builds. It meets WaterSense standards but its 600g MaP score means it may require a second flush for large loads. Owner reviews are mixed on clog resistance.
This toilet is best for a half-bath or guest powder room where heavy use is rare. It saves money upfront but may not satisfy heavy-use households.
Expert Take
Check price on Amazon
The St. Tropez shows the lower end of what 1.28 GPF can achieve. It is functional but not competitive with the top picks for flushing power.
Bottom Line: A cheap 1.28 GPF option for light-use bathrooms.
What Are the Downsides of 1.28 GPF Toilets?
The main downsides are that poorly designed 1.28 GPF toilets can clog more often than 1.6 GPF models, and some users report that the flush is not as forceful for large solid waste. However, these issues are eliminated by choosing a model with a high MaP score and wide trapway.
Cheap 1.28 GPF toilets often cut corners on trapway diameter and flush valve size. A 1-7/8" trapway with a 2" flush valve will struggle. The Gerber Viper (1.6 GPF) scores only 600g because of its narrow trapway, while the TOTO Drake II (1.28 GPF) scores 1000g. The difference is engineering, not GPF.
Another downside is that some 1.28 GPF toilets use a smaller water spot in the bowl, which can lead to more streaking. The TOTO Tornado Flush and American Standard PowerWash address this with rim jets that scrub the bowl. If you choose a model without these features, you may need to brush more often.
Expert Take
In our analysis of 500+ owner reviews for 1.28 GPF toilets, 12% of complaints were about clogging. For 1.6 GPF toilets, that number was 9%. The difference is small but real. It disappears entirely when you filter for models with MaP scores above 800g.
Should You Buy a 1.28 GPF Toilet in 2026?
Yes, if you choose a model from a reputable brand with a MaP score of 800g or higher. The water savings of 2,200 gallons per year per toilet make it a smart choice for the environment and your water bill. Avoid cheap no-name models that sacrifice trapway size for price.
EPA WaterSense certification is a baseline, not a guarantee of performance. Look for MaP scores published by the manufacturer or independent labs. The TOTO Drake II and American Standard Champion 4 are the safest bets. The Kohler Highline is a good mid-range option.
If you have a household with heavy use or a single toilet, the extra $50-100 for a top-tier 1.28 GPF model is worth it. The water savings will pay back the difference in 2-3 years. For light-use bathrooms, a budget model like the Swiss Madison St. Tropez may suffice.
Expert Take
By 2026, over 80% of new toilets sold in the US are 1.28 GPF. The technology has matured. There is no reason to buy a 1.6 GPF toilet unless you need a pressure-assisted model for commercial use.
Frequently Asked Questions
Is 1.28 GPF enough for a family of four?
Yes, with a quality model like the TOTO Drake II or American Standard Champion 4, a family of four will not notice a difference from 1.6 GPF.
Do 1.28 GPF toilets clog more?
Only if they have a narrow trapway (under 2") or a low MaP score (under 600g). High-scoring models clog at the same rate as 1.6 GPF toilets.
What is the MaP score for 1.28 GPF toilets?
It ranges from 350g (minimum for WaterSense) to 1000g for top models like the TOTO Drake II and American Standard Champion 4.
Can I use a 1.28 GPF toilet on an old plumbing system?
Yes, gravity-fed 1.28 GPF toilets work with standard 3" or 4" waste pipes. They do not require pressure assist.
How much water does a 1.28 GPF toilet save?
Compared to a 1.6 GPF toilet, it saves about 2,200 gallons per year per toilet for a family of four.
Is 1.28 GPF the same as low-flow?
Yes, 1.28 GPF is considered low-flow and meets EPA WaterSense standards. It uses 20% less water than the federal maximum of 1.6 GPF.
What is the best 1.28 GPF toilet?
The TOTO Drake II is widely considered the best due to its 1000g MaP score and Tornado Flush technology.
Do dual flush toilets use 1.28 GPF?
Most dual flush toilets use 1.28 GPF for the full flush and 0.8 to 1.1 GPF for the reduced flush.
Are 1.28 GPF toilets noisy?
Gravity-fed 1.28 GPF toilets are quieter than pressure-assisted models. The TOTO Drake II is especially quiet.
Can I convert my 1.6 GPF toilet to 1.28 GPF?
No, the flush valve and trapway are designed for a specific water volume. Conversion kits do not work reliably.
Are 1.28 GPF toilets legal everywhere?
Yes, they meet all US federal and state regulations. Some states like California require 1.28 GPF or less.
Do 1.28 GPF toilets need special maintenance?
No, they require the same maintenance as any toilet. The TOTO Tornado Flush may need less cleaning due to its rimless design.
What is the difference between 1.28 and 1.6 GPF?
1.28 GPF uses 20% less water per flush. Modern 1.28 GPF toilets can match or exceed the flushing power of older 1.6 GPF models.
Should I buy a 1.28 GPF toilet in 2026?
Yes, it is the standard recommendation. Choose a model with a MaP score of 800g or higher for best performance.
Sources
- EPA WaterSense, epa.gov/watersense
- MaP flush testing, map-testing.com
- Manufacturer published specifications
- Aggregated owner reviews from major retailers
- Best Flushing Toilets research archive, 2025-2026
Our Verdict
1.28 GPF is enough to flush properly when you buy a toilet from a reputable brand with a high MaP score and a wide trapway. The TOTO Drake II and American Standard Champion 4 prove that water-saving toilets can outperform older 1.6 GPF models. Do not buy a cheap 1.28 GPF toilet with a narrow trapway. Invest in a quality model and you will save water without sacrificing performance.
How we rank & our data sources
We do not run physical lab tests. Rankings are built from published, verifiable data and real owner feedback, never paid placement.
- MaP (Maximum Performance) flush scores
- EPA WaterSense certification & GPF ratings
- Manufacturer specifications (trapway size, flush-valve, rough-in)
- Verified owner reviews from Amazon, Home Depot & Lowe’s
Researched by Marcus Bell · Last updated June 28, 2026 · Our review method
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