Water, Waste & Recycling
Where does water from the toilet go?
The short answer
Flushing sends used water down a drainpipe. In homes connected to sewers, underground sewers normally carry it to a wastewater treatment plant. There it is cleaned before returning to a river or another body of water.
Flushing does not make the dirt disappear.
See how it works
Arrows show the usual sewer route. Drinking water uses a separate supply.
1. Out of the home
Toilets, showers and sinks have drains. Used water is called wastewater. A pipe carries it out of the home; the drinking-water supply is a different route.
2. Below the street
Smaller drains join larger sewers. A downward slope often helps the water flow. Where that is not enough, pumps lift it higher.
3. To treatment
Sewers carry wastewater to be treated. Not every home is connected: some places use their own small treatment systems. Our diagram shows a common sewer route.
4. Back to a waterway
Treated water returns to rivers or other waterways. That does not make it drinking water. Drinking-water supplies have their own collection, treatment and checking steps.
An imagined Wusel scene
Puschel and Flauschi investigate
At the museum, Puschel follows a pipe through a model town and looks for its end beneath the house. Flauschi finds the sewer continuing onward. They discover that water’s journey goes on after flushing.
Word help
- Sewer system
- An underground network carrying wastewater onward.
- Slope
- A change in height: the route goes downward in the direction of flow.
Your activity
Draw a home, sewer, treatment plant and river. Connect them in that order. Beside them draw a separate drinking-water pipe. Do not accidentally connect the two routes directly.
Quiz: understand the idea
Why is the treatment plant important on this route?
Choose a), b) or c), then explain your choice.
- a)It treats wastewater before it returns to a waterway.
- b)It only stores large waste; the water needs no treatment.
- c)It treats only rainwater, not used water.
Show the explanation
Correct: a): It treats wastewater before it returns to a waterway.
Sewers transport wastewater; the plant treats it. These are different jobs.
Try a new example
A sewer cannot slope downhill here. What could help move the water?
Choose a), b) or c), then explain your choice.
- a)A wider pipe without a pump or slope.
- b)A pump that lifts the wastewater.
- c)A finer screen in the pipe that raises the water.
Show the explanation
Correct: b): A pump that lifts the wastewater.
Pumps can raise water where a natural downward slope is not enough.
Explore in more detail
Here you will find longer explanations and further details. You can explore them together.
More to discover
Rain does not always take the same route
Some places collect rainwater and sewage together; others separate them. Our model therefore does not show every pipe in a real town. Heavy rain can add extra strain. Local water services explain the routes in your area. During very heavy rain, some combined systems can overflow diluted, untreated wastewater into waterways.
Pictures and sources for adults
Sources
Museum scene: AI-generated illustration, checked separately from the factual diagram. The diagrams simplify the process. Editorial source check: 19 October 2026.