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PRODUCT SPECIFICATIONS

Gerber GDF20528

Gerber brand profile & all models

Source rating — not measured installation performanceRecorded rating (US gal/flush)Full flush: 1.1Reduced flush: 0.901.5
Chart generated from this record's EPA snapshot fields. Shared zero baseline; units shown above. This is not a measured flow or flush test.
Tank recordBowl record
Component identification schematic, not to scale. No installation dimensions or compatibility approval are implied.

Compare recorded specifications

Same source category and product or flush type. These are source-record comparisons, not compatible replacements or performance recommendations. Equal ratings do not make two models identical.

Historical EPA source fields; unknown values remain unknown
ParameterGerber GDF20528OVE DECORS ForresOVE DECORS DerryOVE DECORS Tuga
Source model nameVIPER®Not suppliedNot suppliedNot supplied
Rated flush volumefull: 1.1 / reduced: 0.9 US gal/flushfull: 1.6 / reduced: 1.1 US gal/flushfull: 1.6 / reduced: 1.1 US gal/flushfull: 1.6 / reduced: 1.1 US gal/flush
Flush typeDualDualDualDual
Source bowl model numberGWS21528Not suppliedNot suppliedNot supplied
Source tank model numberGDF28528Not suppliedNot suppliedNot supplied
Flush mechanismGravityGravityGravityGravity

Model specifications

Recorded in the EPA directory snapshot of 2026-10-30
ParameterRecorded value
Source bowl model numberGWS21528
Brand as reportedGerber
Flush mechanismGravity
Flush typeDual
Rated flush volumefull: 1.1 / reduced: 0.9 US gal/flush
Source model nameVIPER®
Source model numberGDF20528
Source tank model numberGDF28528

Full and reduced flush volumes remain separate. Counts of uses are needed to estimate consumption; compatibility and installation conditions are not provided.

Source: EPA WaterSense directory. Sources & Methods.

Other source models to examine

Same category and recorded type; these are navigation examples, not recommended substitutes or compatibility matches.

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