Is a 1000g MaP Score Always Better? The Truth

The MaP testing program, run by a consortium of water utilities and manufacturers, uses a standardized test medium (soybean paste and toilet paper) to simulate solid waste. A score of 350g is the minimum for WaterSense certification, 600g is considered good, 800g excellent, and 1000g the maximum tested. However, the test is performed under ideal conditions: a single flush with no pre-wetting, a clean bowl, and a specific drainline configuration. Real-world plumbing varies widely, and a 1000g score does not guarantee a clog-free experience in your home.

Many homeowners assume a higher score means a better toilet, but the test only evaluates one aspect of performance: the ability to move a large mass through the trapway. It does not account for bowl wash, rim cleaning, or how the toilet handles smaller, more frequent flushes. A toilet that scores 1000g may still leave streaks or require multiple flushes for paper, while a 600g model with a superior bowl design might perform better in daily use.

The average human waste load is around 200-400 grams per flush, according to plumbing studies. Even with toilet paper, a typical flush rarely exceeds 500 grams. A toilet with a 600g MaP score handles this easily, while an 800g model provides a comfortable margin. The 1000g threshold is designed for high-demand environments like office buildings, schools, or stadiums where multiple users may flush large volumes simultaneously.

There is a common misconception that a higher MaP score prevents clogs. In reality, clogs are often caused by improper installation, old plumbing, or flushing non-biodegradable items. A 1000g toilet may actually be more prone to clogs if its trapway design is too large or if the flush is too powerful, as it can push waste further into the drain before breaking down. Many plumbers recommend a balanced design over a maximum score.

The MaP test is performed at the toilet's rated GPF (gallons per flush). A toilet that scores 1000g at 1.6 GPF will likely score lower at 1.28 GPF. WaterSense-certified toilets must flush at least 350g using 1.28 GPF or less, but many 1000g models exceed this water usage. This means a higher MaP score can come at the cost of water efficiency, which increases your utility bill and environmental impact.

Noise is another factor. High-scoring toilets often use powerful siphonic or pressure-assisted flush mechanisms that are noticeably louder than standard gravity models. In a quiet home, this can be disruptive, especially at night. Additionally, the aggressive flush may not clean the bowl as thoroughly, requiring more manual cleaning. Some users report that 1000g toilets leave debris behind because the water exits too quickly to rinse the sides.

Clogs typically occur when waste gets stuck in the trapway or drainline. The MaP test uses a straight, clean pipe with a specific diameter (typically 3 inches). In real homes, pipes may have bends, buildup, or smaller diameters (2 inches in older homes). A 1000g toilet that pushes waste with high velocity may actually cause clogs downstream if the waste doesn't break up properly. Many plumbers recommend a toilet with a wider trapway (2-1/8 inches or more) and a slower, more controlled flush for better overall performance.

Another factor is the type of flush. Gravity-fed toilets use water weight to create a siphonic action, which is gentle on pipes. Pressure-assisted toilets use compressed air to force water out, which can be harder on older plumbing. While pressure-assisted models often score higher on MaP tests, they are not necessarily better for home use. The TOTO Drake with a 1,000g MaP score is a popular choice because it combines a wide trapway with a quiet, efficient gravity flush that rarely clogs.

In households with heavy use, such as multiple bathrooms shared by many people, the extra capacity can reduce the frequency of flushes and potential clogs. Commercial restrooms in offices, restaurants, or schools benefit from 1000g toilets because they handle high traffic and larger waste loads. Similarly, if your home has a long drainline (over 20 feet) or a shallow slope, a more powerful flush may help move waste through the system.

However, for the average family of 2-4 people, a 1000g toilet is unnecessary. The American Standard Champion 4 with a 800g MaP score is a reliable choice that offers excellent performance without the drawbacks of a maximum-score model. It uses a 4-inch flush valve and a wide trapway to move waste efficiently, and it is WaterSense certified at 1.28 GPF. Many homeowners find it handles everything they need without the noise or water waste of a 1000g toilet.

Manufacturers publish MaP scores for their toilets, but they are not always easy to find on product pages. You can search the MaP database at map-testing.com for specific models. For example, the Kohler Highline has a MaP score of 800g, while some TOTO models score 600g and others 1000g. The score depends on the bowl design, trapway size, and flush mechanism, not just the brand name.

When comparing toilets, look at the full picture: MaP score, GPF, bowl shape (elongated vs. round), and rough-in size (10, 12, or 14 inches). A 12-inch rough-in is standard for most homes. Also consider the flush type: gravity, pressure-assisted, or dual-flush. Dual-flush toilets often have lower MaP scores for the half-flush (around 350g) but higher for the full flush (600-800g). This can be a good compromise for water savings.

• EPA WaterSense, epa.gov/watersense
• MaP Flush Testing Program, map-testing.com
• Manufacturer published specifications
• Plumbing industry studies on waste load averages