1.6 GPF vs 1.28 GPF — which should you buy?
The 1992 federal mandate dropped US toilets from 3.5+ GPF to 1.6 GPF. The 2007 WaterSense voluntary spec dropped further to 1.28 GPF. By 2014, several states (CA, CO, GA, TX, NY) mandated 1.28 GPF for new construction. But for replacement toilets in older housing, 1.6 GPF often remains the better choice.
When 1.6 GPF is the right answer
- Pre-1980 housing with original cast-iron or galvanized drainlines still in use
- Long horizontal drainline runs (25+ feet) at minimum 1/8" per foot slope
- Replacement of an existing 1.6 GPF toilet in a building where 1.28 GPF retrofits have already caused problems
- Rental properties where 1.28 GPF has caused tenant clog complaints
- Heavy paper users / large households where modern 1.28 GPF flush struggles
- States without 1.28 GPF mandates (most US outside CA, CO, GA, TX, NY)
When 1.28 GPF is the right answer
- Modern drainlines (1995+ ABS or PVC) properly sized for 1.28 GPF flow
- New construction in WaterSense-mandate states
- Owner-occupied long-term home wanting utility rebate eligibility
- LEED-certified buildings or green-renovation projects
- Light-use households (1-2 person, light paper use)
The 1.28 GPF vs 1.6 GPF state mandate map
| State | 1.28 GPF mandate | Effective date |
|---|---|---|
| California | Required for new construction | 2014 |
| Colorado | Required for new construction | 2016 |
| Georgia | Required for new construction | 2012 |
| Texas | Required for new construction | 2014 |
| New York | Required for new construction | 2014 |
| All other US states | 1.6 GPF allowed for residential replacement | — |
Note: 1.6 GPF residential replacement (not new construction) is generally allowed even in mandate states. Verify with local plumbing inspector before purchase.
Best 1.6 GPF toilets (for old-drainline replacement)
| Brand | Model | Price (~) | Key strength |
|---|---|---|---|
| Mansfield | Pro-Fit 1 | $150-$200 | Commercial-grade trapway + 5-year tank trim warranty |
| Mansfield | Maverick | $170-$240 | Elongated + Comfort Height variant of Pro-Fit |
| Eljer | Hamilton | $140-$200 | USA-made + 5-year tank trim + Eljer brand pedigree |
| Gerber | Maxwell | $160-$220 | Commercial-grade trapway + plumber-channel sourcing |
| Sterling | Plymouth Plus | $110-$160 | Lowest cost Kohler-family 1.6 GPF |
| American Standard | Mainstream 1.6 Round | $150-$190 | AmStd brand + widest retail availability |
| Kohler | Wellworth Round | $168-$240 | Kohler brand + 1.6 GPF residential |
Best 1.28 GPF toilets (for modern drainlines)
| Brand | Model | Price (~) | Key strength |
|---|---|---|---|
| TOTO | Drake II | $330-$470 | Best flush technology + CeFiONtect glaze |
| Kohler | Cimarron | $200-$300 | AquaPiston canister + Kohler brand |
| American Standard | Cadet 3 | $170-$260 | EverClean glaze + 5-year warranty |
| Sterling | Stinson | $130-$180 | Lowest-cost Kohler-family |
| Vortens | 3464 | $129-$179 | Home Depot Sun Belt + lifetime porcelain |
| Glacier Bay | All-in-One Elongated | $109-$159 | Lowest absolute cost + bundled seat |
What about 0.95 GPF Niagara Stealth?
The Niagara Stealth ($240-$340) uses 0.95 GPF — 26% lower than WaterSense 1.28 GPF. The vacuum-assist trapway compensates for the low water volume, maintaining bowl evacuation. The Niagara Stealth is the most water-efficient single-flush toilet in US residential — but only for modern drainlines properly sized for low-flow flush velocity.