AT A GLANCE
Four largest reported groups
Counts of accepted identities. The complete distribution and denominator follow below.
One flush volume is not always enough
There are 3,813 Single and 2,778 Dual identities in the fixed 6,591-record population. All have a usable parsed flush field, but a dual-flush pair must remain two values. The reduced value is not the amount used by every flush.
| Source value | Product identities | Share of category |
|---|---|---|
| 1.28 (reported scalar) GPF | 3,226 | 48.95% |
| Full 1.6 / Reduced 1.1 GPF | 1,238 | 18.78% |
| 1 (reported scalar) GPF | 328 | 4.98% |
| Full 1.28 / Reduced 0.8 GPF | 320 | 4.86% |
| Full 1.6 / Reduced 0.8 GPF | 306 | 4.64% |
| Full 1.28 / Reduced 1 GPF | 144 | 2.18% |
| 0.8 (reported scalar) GPF | 121 | 1.84% |
| Full 1.6 / Reduced 1 GPF | 111 | 1.68% |
| Full 1.28 / Reduced 0.9 GPF | 99 | 1.50% |
| Full 1 / Reduced 0.8 GPF | 79 | 1.20% |
| Full 1.28 / Reduced 1.06 GPF | 72 | 1.09% |
| Full 1.28 / Reduced 0.92 GPF | 66 | 1.00% |
| Full 1.28 / Reduced 1.05 GPF | 51 | 0.77% |
| 1.1 (reported scalar) GPF | 50 | 0.76% |
| Full 1.6 / Reduced 1.06 GPF | 43 | 0.65% |
| Other reported values | 337 | 5.11% |
Denominator: 6,591 accepted identities; known field values: 6,591; UNKNOWN: 0. Shares describe this saved catalog, not sales or household installations.
Two equivalent ways to calculate
Single flush daily volume = reported GPF × daily flush count. Dual flush daily volume = full GPF × full-flush count + reduced GPF × reduced-flush count. Keep all units in US gallons per flush.
Illustrative assumptions: five single flushes at 1.28 GPF total 6.4 gallons. Two full flushes at 1.6 GPF plus three reduced flushes at 1.1 GPF total 6.5 gallons. That 0.1-gallon difference is a scenario result, not a general claim that single or dual flush is better.
Why a catalog average can mislead
Averaging the smallest number from each dual-flush row would discard the full mode. An effective flush volume also requires an assumed mix of full and reduced use. This page therefore reports pairs and counts, not one unconditional cross-model efficiency score.
What the mechanism field adds
The source records list Gravity for 6,015 identities, Pressure Assist for 472 and Other for 104. These labels help organize research; they do not supply rough-in dimensions, bowl-and-tank compatibility, installation constraints or comparable waste-removal measurements.
Enter separate full and reduced counts and inspect the calculation. Review how composite source values are preserved before interpreting a model.
Source: EPA WaterSense product directory, saved 30 October 2026; this analysis uses the fixed catalog release described in Sources and research methods. These historical observations do not establish current certification or product availability. Fixture Flow Atlas is independent of EPA; no affiliation or endorsement is claimed.