How Does a Toilet Work? #wastewater #toilet

[0:00]Have you ever wondered what happens when you flush a toilet? How does it work exactly? Let's take a look at the clever engineering behind these devices we rely on every day. Inside the tank, you'll find a few key parts: the chain, fill valve, refill tube, flapper, and overflow tube. When you press the handle to trigger a flush, the handle pulls the chain, lifting the flapper at the bottom of the tank. Water then rushes from the tank through the rim and into the bowl, causing the flush. But what exactly causes the water and waste to get flushed out of the bowl? Inside the toilet is a curved passage called the trapway. Between flushes, water sits just below the bend in the trapway. During a flush, water rushes in from the rim and from a passage called a siphon jet, which leads directly into the trapway. The surge of water causes the water level to rise over the bend. Gravity then pulls the water down the trapway, creating a siphon. The siphon will continue to pull everything in the bowl out through the trapway until air interrupts the flow, stopping the siphon. Back in the tank, as the water level lowers, the flapper will drop, sealing the tank, stopping any more water from flowing into the bowl. Now that the flush is complete, both the bowl and the tank need to be refilled. But how does a toilet know when to start refilling and when to stop? That brings us to the fill valve. As water from the tank empties during a flush, a float attached to the fill valve will drop. This opens a seal inside the valve. Because of the pressure difference from releasing the seal, water will now flow from a supply hose and through the fill valve, filling the tank. To fill the bowl, some water will be diverted into the refill tube. This water flows into the overflow tube, which leads directly to the bowl. As the tank fills, the float rises. When it reaches the right level, the fill valve is again sealed, and the water flowing into the tank and bowl is stopped. And just like that, everything's ready for the next flush.