Tank vs flushometer toilets: where the flushing water comes from
A tank toilet stores its flush water in a tank behind the bowl. A flushometer has no tank: it sends water from the supply line through a flush valve straight into the bowl.
Where the water waits before a flush
The difference, line by line
Where the flush water waits
Tank: In a tank behind the bowl.
Flushometer: Nowhere. There's no tank; the water comes from the supply line.
What sends it into the bowl
Tank: Gravity when a flapper valve opens, or air pressure in a pressure-assisted tank.
Flushometer: Pressure from the supply line, through a flush valve.
Where you usually find it
Tank: Typically in homes.
Flushometer: Common in commercial buildings.
Types
Tank: 2Gravity-style and pressure-assisted.
Flushometer: 1A product category of its own.
Inside a tank toilet
Gravity-style
Water waits in the tank. When you flush, a flapper valve between the tank and the bowl opens and the water falls into the bowl.
Pressure-assisted
The tank holds a sealed vessel with pressurized air inside. When you flush, the air pushes the water into the bowl at high speed, for a stronger flush. It's still a tank toilet.
What this doesn't tell you
Which toilet is in your home, or how much water, noise, reliability or cost to expect. “Typically” and “common” describe where each type is usually found, not a rule for every building. This is not a product recommendation or a repair guide.