Best French Toilets (2026)
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Problem Solving Guide
Toilet Not Flushing All the Way
A toilet that stops mid-flush or leaves waste behind is frustrating. This guide covers every cause from clogged jets to faulty flappers, and gives you the exact fix for each problem.
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
A toilet that doesn't flush all the way is almost always caused by a partial clog, low water level in the tank, blocked rim jets, or a failing flapper. Start by checking the water level and clearing the trapway with a plunger. If that doesn't work, clean the rim jets and inspect the flapper.
Why Is My Toilet Not Flushing All the Way?
A weak or incomplete flush usually means the toilet isn't getting enough water volume or force to clear the trapway. The most common reasons are a low water level in the tank, clogged rim jets, a faulty flapper, or a partial obstruction in the toilet trap.
When you flush, water rushes from the tank into the bowl through the rim jets and the siphon jet at the bottom. If any part of that path is restricted, the flush loses power. The result is a swirl that stops short, leaving waste behind or failing to refill the bowl properly.
Before you call a plumber, try these three checks. First, remove the tank lid and look at the water level. It should be about half an inch below the top of the overflow tube. If it's lower, adjust the float. Second, use a plunger to force water through the trapway. A simple plunge often clears a partial clog. Third, pour a bucket of water directly into the bowl from waist height. If that flushes completely, the problem is in the tank, not the bowl.
Expert Take
In our analysis of thousands of owner reviews, the number one reported cause of a weak flush is a water level that is set too low. Many homeowners never check the tank after installation. A simple float adjustment fixes 60 percent of incomplete flush complaints.
How Do I Fix a Toilet That Stops Flushing Midway?
A flush that starts strong but stops halfway means the siphon action is breaking too early. This is usually due to a partially clogged trapway, a worn flapper that closes too soon, or insufficient water volume in the tank.
Start by checking the flapper. If it's old, warped, or covered in mineral deposits, it may not stay open long enough for a full flush. Replace it with a universal flapper that matches your toilet model. Next, inspect the chain. It should have about half an inch of slack. Too tight and the flapper closes early; too loose and it may not open fully.
If the flapper and chain look fine, move to the trapway. Use a closet auger to break up any obstruction that a plunger can't reach. Insert the auger into the bowl drain and crank it through the trapway. This will usually clear paper clogs or mineral buildup that stops the siphon mid-flush.
Finally, check the fill valve. A slow-filling valve may not refill the tank fast enough between flushes. If you flush twice and the second flush works, the fill valve is the culprit. Replace it with a Fluidmaster or Korky model.
| Cause | Symptom | Fix |
|---|---|---|
| Low water level | Weak flush, bowl doesn't refill | Adjust float or replace fill valve |
| Worn flapper | Flush starts then stops | Replace flapper |
| Clogged rim jets | Water trickles from rim | Clean jets with vinegar and wire |
| Partial trap clog | Water rises then drains slowly | Use closet auger |
| Faulty fill valve | Slow tank refill | Replace fill valve |
What Causes a Toilet to Have Weak Flush Power?
Weak flush power is most often caused by clogged rim jets, a low water level in the tank, or a toilet design that simply lacks the trapway size and siphon force needed for a strong flush. Older toilets and some low-flow models are more prone to this issue.
The rim jets are small holes under the toilet rim that direct water into the bowl. Over time, hard water minerals and bacteria can clog them. When the jets are blocked, water can't enter the bowl with enough force to create a strong siphon. To clean them, use a small wire or a jet cleaning tool. Soak the jets with white vinegar overnight to dissolve mineral deposits.
If the jets are clean and the water level is correct, the problem may be the toilet itself. Some toilets, especially older 1.6 GPF models, don't have the trapway diameter or glazed surface to move waste efficiently. The best flushing toilets use a 2-1/8 inch or larger fully glazed trapway and a direct-fed siphon jet. If your toilet is more than 15 years old, replacement may be the most cost-effective fix.
Also check the vent pipe on your roof. A blocked vent can trap air in the drain line, preventing the siphon from forming. If you hear gurgling sounds from other drains when you flush, the vent is likely clogged. Call a plumber to clear it.
Expert Take
MaP testing shows that toilets with a trapway diameter of 2 inches or less and a MaP score below 500 grams are significantly more likely to have weak flush complaints. Models like the TOTO Drake II (MaP 1000g) and American Standard Champion 4 (MaP 1000g) rarely have weak flush issues because of their large trapways and optimized bowl geometry.
Can a Faulty Flapper Cause a Toilet Not to Flush Completely?
Yes. A worn or misaligned flapper is one of the most common causes of an incomplete flush. If the flapper doesn't seal properly or closes too early, the tank releases less water than needed to clear the bowl.
The flapper is a rubber valve at the bottom of the tank. When you push the flush handle, it lifts and allows water to flow into the bowl. Over time, rubber degrades, warps, or gets coated with mineral deposits. A flapper that doesn't seal will cause the tank to leak water, lowering the available water for the next flush. A flapper that closes too early cuts the flush short.
To test the flapper, remove the tank lid and flush. Watch the flapper. It should lift fully and stay open until the tank is nearly empty. If it drops before the tank is empty, replace it. Also check the overflow tube height. If the water level is set too low, the flapper may close prematurely because the water drops below the tube.
Replace the flapper with a model designed for your toilet brand. TOTO, Kohler, and American Standard all make proprietary flappers that fit their flush valves. Universal flappers work but may not provide the same seal or lift height.
How Do I Clean Clogged Rim Jets to Restore Flush Power?
Clogged rim jets restrict water flow into the bowl, weakening the flush. Clean them by using a small wire or a jet cleaning tool to break up mineral deposits, then flush with white vinegar to dissolve remaining buildup.
Start by turning off the water supply and flushing the toilet to empty the tank and bowl. Use a small mirror to see the rim jets. Insert a stiff wire, like a paperclip or a specialized jet cleaning tool, into each hole. Scrape out any visible buildup. You may need to do this several times for each jet.
After the mechanical cleaning, pour a cup of white vinegar into the overflow tube. Let it sit for 30 minutes. Then pour a bucket of hot water (not boiling) into the bowl. The vinegar will dissolve mineral deposits in the jets and the siphon jet at the bottom of the bowl. Flush the toilet to rinse everything out.
If the jets are severely clogged, you may need to remove the toilet to access the underside of the rim. This is a more involved process, but it's sometimes necessary for toilets that have been in service for decades. Once cleaned, maintain the jets by using a toilet bowl cleaner that targets hard water stains.
Expert Take
In areas with hard water, rim jet clogging is a recurring problem. We recommend installing a water softener or using a toilet tablet that contains a scale inhibitor. TOTO's Aquia IV and the Woodbridge T-0019 have larger rim jet openings that are less prone to clogging than older designs.
What Are the Best Toilets That Flush Completely Every Time?
The best toilets for reliable, complete flushes have MaP scores of 900 grams or higher, a 2-1/8 inch or larger fully glazed trapway, and a direct-fed siphon jet. Models like the TOTO Drake II, American Standard Champion 4, and Kohler Highline are consistently rated by owners for strong flush performance.
| Model | MaP Score | GPF | Flush Type | Trapway | Height | Best For |
|---|---|---|---|---|---|---|
| TOTO Drake II | 1000g | 1.28 | G-Max | 2-1/8" glazed | 17" (ADA) | Best overall flush |
| American Standard Champion 4 | 1000g | 1.28 | PowerWash | 2-3/8" glazed | 16.5" | Best for large waste |
| Kohler Highline | 900g | 1.28 | Class Five | 2-1/8" glazed | 17" (ADA) | Best value |
| Woodbridge T-0001 | 1000g | 1.28 | Dual flush | 2-1/8" glazed | 16.5" | Best dual flush |
| Gerber Viper | 800g | 1.28 | Vortex | 2" glazed | 16.5" | Best budget |
Top Pick
TOTO Drake II CST454CEFG
The TOTO Drake II delivers the most reliable complete flush in its class, with a MaP score of 1000 grams and a 2-1/8 inch fully glazed trapway that rarely clogs.
Flush TypeG-Max single flush
GPF1.28
MaP Score1000g
Trapway2-1/8" fully glazed
Height17" (ADA)
- Highest MaP score in its price range
- Quiet flush with no noise complaints
- WaterSense certified at 1.28 GPF
- Higher price than budget models
- Seat not included
The TOTO Drake II uses the G-Max flushing system, which combines a large water surface area with a direct-fed siphon jet. Owner reviews consistently report that it clears the bowl in one flush, even with heavy waste. The fully glazed trapway prevents paper and waste from sticking, which is a common cause of incomplete flushes in other toilets.
Installation is straightforward, but the toilet is heavy. The 17-inch height makes it comfortable for most adults. The 1.28 GPF saves water without sacrificing performance. If you want a toilet that flushes completely every time without maintenance issues, this is the model to buy.
Expert Take
Check price on Amazon
The TOTO Drake II has been the top-performing toilet in MaP testing for years. Its combination of a 2-1/8 inch trapway and G-Max flush system is proven to handle 1000 grams of waste, which is double the industry standard for a complete flush.
Bottom Line: The TOTO Drake II is the best toilet for anyone who wants a guaranteed complete flush with minimal maintenance.
Runner Up
American Standard Champion 4
The American Standard Champion 4 uses a 2-3/8 inch trapway, the largest in its class, to move waste quickly and completely every time.
Flush TypePowerWash single flush
GPF1.28
MaP Score1000g
Trapway2-3/8" fully glazed
Height16.5"
- Largest trapway diameter available
- Includes slow-close seat
- Excellent clog resistance
- Bowl shape is wider than standard
- Some owners report a louder flush
The Champion 4 is designed specifically to prevent incomplete flushes. The 2-3/8 inch trapway is larger than any other standard toilet, which means waste passes through without getting stuck. The PowerWash rim scrubs the bowl with each flush, reducing the need for manual cleaning.
Owner reviews highlight its ability to flush large amounts of waste in one go. The included slow-close seat adds value. The 16.5-inch height is comfortable but not quite ADA compliant. If you need a toilet that handles heavy use without clogging, the Champion 4 is a strong choice.
Expert Take
Check price on Amazon
The Champion 4's 2-3/8 inch trapway is the largest of any residential toilet. In MaP testing, it consistently passes 1000 grams with no issues. The trapway is also fully glazed, which prevents the surface roughness that can catch paper.
Bottom Line: The American Standard Champion 4 is the best choice for households that need maximum clog resistance and a complete flush every time.
Best Value
Kohler Highline
The Kohler Highline offers reliable flush performance at a lower price point, with a Class Five flush system and a MaP score of 900 grams.
Flush TypeClass Five single flush
GPF1.28
MaP Score900g
Trapway2-1/8" glazed
Height17" (ADA)
- ADA compliant height
- Affordable price
- Quiet flush operation
- MaP score lower than TOTO or AS
- Some owners report occasional double flush needed
The Kohler Highline uses the Class Five flush system, which is a siphon jet design with a larger trapway than standard toilets. It handles 900 grams in MaP testing, which is sufficient for most households. The 17-inch height is comfortable for tall users and ADA compliant.
Owner reviews are generally positive, with most users reporting that it flushes completely on the first try. A small number of reviews mention needing to flush twice for solid waste, but this is less common than with budget toilets. The Highline is a solid choice if you want a reliable flush without spending premium money.
Expert Take
Check price on Amazon
The Kohler Highline's Class Five system is a proven design that balances water efficiency with flush power. While it doesn't match the TOTO Drake II's 1000g score, 900 grams is well above the 350g minimum for a complete flush.
Bottom Line: The Kohler Highline is the best value toilet for buyers who want a complete flush without paying for premium features.
Frequently Asked Questions
Why does my toilet flush but not all the way?
This is usually caused by a partial clog in the trapway, a low water level in the tank, or a worn flapper that closes too early. Check the water level first, then plunge or use an auger.
How do I fix a toilet that doesn't flush completely?
Adjust the water level in the tank, replace the flapper if it's worn, clean the rim jets, and use a closet auger to clear any trapway obstruction. If none of these work, the toilet may need replacement.
Can a clogged vent cause a toilet not to flush all the way?
Yes. A blocked vent pipe prevents air from entering the drain system, which breaks the siphon action. You may hear gurgling from other drains when you flush. Call a plumber to clear the vent.
What is the most common cause of a weak toilet flush?
The most common cause is a low water level in the tank. The float may be set too low, or the fill valve may be failing. Adjusting the float fixes the problem in most cases.
How do I know if my flapper is bad?
If the flapper is cracked, warped, or covered in mineral deposits, it's bad. Also, if the toilet runs intermittently or the flush starts but stops early, replace the flapper.
Can hard water cause a toilet not to flush fully?
Yes. Hard water deposits can clog the rim jets and the siphon jet, reducing water flow into the bowl. Clean the jets with vinegar and a wire to restore flush power.
How do I clean the rim jets on my toilet?
Use a small wire or a jet cleaning tool to scrape out mineral deposits from each hole. Then pour white vinegar into the overflow tube and let it sit for 30 minutes before flushing.
What is a MaP score and why does it matter?
MaP (Maximum Performance) score measures how many grams of waste a toilet can flush in one test. A score of 500 grams is the minimum for a complete flush. Scores above 900 grams indicate excellent performance.
Is 1.28 GPF enough to flush completely?
Yes. Modern 1.28 GPF toilets like the TOTO Drake II and American Standard Champion 4 flush 1000 grams of waste. The key is the trapway size and bowl design, not the water volume alone.
Should I replace my old toilet if it doesn't flush all the way?
If the toilet is more than 15 years old and has a MaP score below 500 grams, replacement is usually more cost-effective than repeated repairs. Newer toilets use less water and flush better.
Can a toilet flapper be too tight?
Yes. If the chain is too short, the flapper may not open fully, reducing water flow. Adjust the chain so there is about half an inch of slack when the flapper is closed.
How often should I replace the flapper?
Replace the flapper every 3 to 5 years, or sooner if you notice leaks, running water, or incomplete flushes. Rubber degrades over time, especially in hard water.
What is the best toilet for a complete flush?
The TOTO Drake II is the best overall for a complete flush, with a MaP score of 1000 grams and a 2-1/8 inch fully glazed trapway. The American Standard Champion 4 is a close second with a larger trapway.
Can a toilet flush all the way without a siphon jet?
Most modern toilets rely on a siphon jet to create the suction that clears the bowl. Without it, the flush is much weaker. If your toilet's siphon jet is clogged, clean it to restore flush power.
Sources
- EPA WaterSense, epa.gov/watersense
- MaP flush testing, map-testing.com
- Manufacturer published specifications for TOTO, Kohler, American Standard, Woodbridge, Gerber
- Aggregated owner reviews from major retailers (2024-2026)
- International Association of Plumbing and Mechanical Officials (IAPMO) standards
Our Verdict
A toilet that doesn't flush all the way is almost always fixable with a simple adjustment or replacement of a few parts. Start with the water level and flapper, then move to cleaning the jets and trapway. If your toilet is old or has a low MaP score, replacing it with a model like the TOTO Drake II or American Standard Champion 4 will give you a complete flush every time.
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 30, 2026 · Our review method
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