Flush Performance & Water Efficiency
Updated February 24, 2026
A toilet that saves water but needs two flushes wastes more. MaP testing provides objective flush performance data. WaterSense ensures efficiency. The best toilets score high on both.
Overview
A toilet that saves water but needs two flushes wastes more. MaP testing provides objective flush performance data. WaterSense ensures efficiency. The best toilets score high on both.
What to Know
MaP Scores
- MaP (Maximum Performance) testing measures grams of solid waste cleared in a single flush.
- 250g is the minimum to pass.
- 500g is good for light residential use.
- 800g+ is excellent and what you should target for a family bathroom.
- The TOTO Drake scores 800-1000g at only 1.28 GPF -- that is the benchmark.
- MaP scores are published at map-testing.com for hundreds of models.
GPF Ratings
- Gallons per flush (GPF).
- Federal maximum is 1.6 GPF since 1994.
- WaterSense certification requires 1.28 GPF or less.
- High-efficiency toilets (HET) hit 1.0-1.1 GPF.
- Lower GPF only matters if the flush actually clears waste in one shot -- a 1.0 GPF toilet that needs two flushes wastes more water than a 1.28 GPF toilet that clears everything the first time.
WaterSense Certification
EPA WaterSense program certifies toilets at 1.28 GPF or less that also pass independent flush performance testing. A family of four saves roughly 13,000 gallons per year upgrading from a 3.5 GPF toilet to WaterSense. Many water utilities offer $50-$200 rebates per toilet for WaterSense models -- check your local utility's website or call them.
Buying Tips
- MaP 800g+ is the most important spec.
- WaterSense at 1.28 GPF saves thousands of gallons per year.
- TOTO Drake is the benchmark: 800-1000g MaP at 1.28 GPF.
- Check for utility rebates on WaterSense toilets.
Common Mistakes
- Choosing 1.0 GPF without checking MaP -- may need double-flushing.
- Ignoring MaP entirely.
- Assuming WaterSense means weak flush.
- Buying based on GPF alone.
Bottom Line
WaterSense certified (1.28 GPF) with MaP 800g+. Saves water AND flushes well.
Frequently Asked Questions
What should I look for when buying flush performance & water efficiency?
MaP 800g+ is the most important spec. WaterSense at 1.28 GPF saves thousands of gallons per year. TOTO Drake is the benchmark: 800-1000g MaP at 1.28 GPF.
What are common mistakes when buying flush performance & water efficiency?
Choosing 1.0 GPF without checking MaP -- may need double-flushing. Ignoring MaP entirely. Assuming WaterSense means weak flush.
What is the bottom line on flush performance & water efficiency?
WaterSense certified (1.28 GPF) with MaP 800g+. Saves water AND flushes well.
What's the bottom line on flush performance & water efficiency?
WaterSense certified (1.28 GPF) with MaP 800g+. Saves water AND flushes well.
What are the top tips for flush performance & water efficiency?
MaP 800g+ is the most important spec.. WaterSense at 1.28 GPF saves thousands of gallons per year.. TOTO Drake is the benchmark: 800-1000g MaP at 1.28 GPF..
What mistakes should I avoid when buying?
Common mistakes: Choosing 1.0 GPF without checking MaP -- may need double-flushing.. Ignoring MaP entirely.. Assuming WaterSense means weak flush..
What are the best toilets brands?
Top brands include American Standard, Aquasource, Briggs, Caroma, Contrac, Danco. Each serves different price points and needs.