Gravityflush

Gravityflush refers to a toilet flush mechanism that relies primarily on gravity to move water from the tank into the bowl and to create the siphon that clears waste. It is the most common type of flush system in traditional gravity-fed toilets and contrasts with pressure-assisted or vacuum-assisted designs.

In operation, the user actuates the flush, which opens the flush valve and releases water from the tank. The rapid flow through the rim jets and into the bowl generates a suction that initiates the siphon, evacuating the bowl and delivering waste into the drain. After the flush, the fill valve restores water in the tank for the next cycle. Most gravity-flush toilets use a flapper or canister-type flush valve and rely on the geometry of the bowl and trapway to maximize performance.

Performance and efficiency considerations often center on flush volume and bowl design. In the United States, standard gravity-flush toilets have historically used about 1.6 gallons (6 liters) per flush, with modern high-efficiency models aiming for 1.28 gallons (4.8 liters) or less. Many jurisdictions also promote low-flow options through labeling programs that emphasize water savings. Design variations, such as optimized siphon jets, larger flush valves, and dual-flush configurations, can affect the balance between water use and flushing power while remaining gravity-driven.

Advantages of gravity-flush systems include simplicity, reliability, and lower maintenance relative to some pressurized systems. Potential drawbacks include variability in flush performance depending on bowl geometry, water pressure, and waste load, as well as slower clearing in older or poorly designed models.