A standard toilet has two main ceramic parts: the bowl and the tank. The bowl is the lower section that holds water and connects to the drainpipe in the floor. Its primary job is to hold waste until you flush.

The tank sits on top of the bowl and holds the reserve of water needed for each flush, typically between 1.28 and 1.6 gallons in modern toilets. It houses the mechanical parts that make flushing possible.

Lifting the tank lid reveals a collection of simple but clever components. These parts work together to release water into the bowl when you flush and then refill the tank for the next use. Let's look at the key players.

Flush Handle: This is the lever or button you press to start the flush. It's connected to a lever inside the tank, which pulls up a chain.

Flapper Valve: The chain is attached to this rubber seal at the bottom of the tank. When the handle is pressed, the chain lifts the flapper, uncovering the drain hole and letting all the water rush from the tank into the bowl. After the flush, the flapper falls back into place, sealing the drain so the tank can refill.

Fill Valve: This mechanism's job is to refill the tank with water after a flush. It’s a tall tube, usually on the left side of the tank. As the water level drops, a float attached to the fill valve goes down, opening the valve to let fresh water in. As the tank fills, the float rises and eventually shuts off the water supply once the correct level is reached.

Overflow Tube: This is a safety feature. It's a tall, open pipe in the middle of the tank. If the fill valve fails to shut off, this tube directs the excess water down into the bowl instead of letting it overflow onto your bathroom floor. The fill valve also sends a small amount of water down this tube via a smaller hose to refill the bowl after a flush.

Understanding these parts is the first step to figuring out how a toilet works and how to fix common problems, like a toilet that won't stop running.