Dual-Flush Toilets
Updated February 20, 2026
Feature two flush options — a lower-volume flush for liquid waste and a full flush for solid waste. Designed to conserve water without sacrificing performance.
Overview
Dual-flush toilets have two flush options: a low-volume flush (0.8-1.0 GPF) for liquid waste and a full flush (1.28-1.6 GPF) for solids. Two buttons on top of the tank or a two-position handle. They save 25-40%% water compared to standard single-flush toilets. Common in water-conscious regions and increasingly popular nationwide. The mechanism is typically a valve-based flush (not a flapper), which is more durable but different to service than traditional toilets.
Pros & Cons
- Water saving
- Eco-friendly
- Two flush options
- More complex mechanism
- Buttons may wear over time
Key Features
- Two flush volumes: light (0.8-1.0 GPF) and full (1.28-1.6 GPF)
- Saves 25-40%% water compared to single-flush 1.6 GPF toilets
- Button-style flush actuator on top of the tank (most common) or dual-position handle
- Valve-based flush mechanism instead of traditional flapper
- WaterSense certified models qualify for utility rebates in many areas
Sizing & Selection
Same rough-in dimensions as standard toilets: 10-inch, 12-inch (most common), or 14-inch rough-in. Measure from the wall (not baseboard) to the center of the closet bolts. Bowl shape: round (compact, 16.5 inch) or elongated (more comfortable, 18.5 inch). Elongated is standard for most new installations.
Installation
Identical to any standard toilet: set wax ring on flange, lower toilet onto bolts, connect water supply. The dual-flush valve mechanism installs inside the tank during assembly. No special plumbing required. Some models are one-piece (tank and bowl integrated), others are two-piece (separate tank bolts onto bowl).
Maintenance
- The dual-flush valve is different from a flapper -- it uses a tower or canister that lifts vertically.
- Clean the valve seal annually. Remove the canister, wipe the seal and seat with a cloth.
- If one flush mode stops working, the actuator cable or button mechanism may need adjustment or replacement.
- Descale the rim holes with vinegar and a brush every 6-12 months for consistent flush performance.
Buying Tips
- TOTO, Kohler, and American Standard make the most reliable dual-flush models.
- WaterSense certified models use 1.28 GPF or less on the full flush -- these qualify for rebates.
- Test the light flush before committing. Some cheap dual-flush toilets have a light flush that does not adequately clear the bowl.
- Button-top flush is the most common but can be confusing for guests. Label or choose a model with clearly differentiated buttons.
- Budget -500 for a quality dual-flush toilet. Cheap models (-150) often have unreliable flush mechanisms.