Mexico City and Tehran – Water and Air Challenges (ESL Level 4)

Big cities, big problems: water and air in two mountain basins.

Short ESL Summary

1. Simple Explanation (Level 4)

Mexico City and Tehran are both huge cities in mountain basins. Millions of people live there, and both cities are very important for their countries.

They have two big problems that affect daily life:

Air pollution: Many cars, trucks, and factories make dirty air. The mountains around the cities trap the pollution, so the smog often stays for days.
Not enough water: Both cities use more water than nature can replace. Drought and climate change make the problem worse.

In Mexico City, most water comes from underground aquifers. People have pumped so much water that the ground is sinking in some places. Pipes break, streets crack, and it is very hard to fix the system.

In Tehran, much of the water comes from dams and reservoirs in the nearby mountains. Years of low rain and less snow mean that many of these dams are now very low. Officials sometimes must cut water or reduce pressure.

For many families in both places, water does not always come when they open the tap. Some homes use tanks on the roof or store water in big bottles. People also worry about breathing the air, especially children and older adults.

Side-by-Side View

2. Comparison Table – Mexico City vs. Tehran

This table compares the main water and air problems in both cities.

Topic	Mexico City	Tehran
Main water source	Mostly underground aquifers beneath and near the city.	Mainly dams and reservoirs in the Alborz Mountains, plus some groundwater.
Main water problem	Over-pumping the aquifers. The ground is compacting and the city is sinking.	Reservoirs are extremely low after years of drought and less snow.
Water losses	Old, damaged pipes leak a great deal of water before it reaches homes.	Leaks exist, but the main stress is not enough water in the dams.
Everyday impact	Some neighborhoods get water only at certain hours or days.	Families often face low pressure or temporary shut-offs.
Air pollution	Traffic + basin geography trap smog for days.	Similar basin shape traps pollution near the ground.
Long-term risk	Aquifer compaction is mostly permanent.	If dams stay low, city may require strict rationing.
Shared issue	Both cities use water faster than nature can replace it—and both fight severe smog in a mountain basin.

Map-Based Explanation (Text)

3. How Geography Makes These Problems Worse

Mexico City on the map

Mexico City is in central Mexico, high above sea level in a wide valley. Mountains and hills stand around much of the city. Long ago, lakes filled the basin, but most were drained as the city expanded.

Because of this shape:

Air stays trapped during still weather, creating smog.
Water must come from aquifers or faraway rivers.

Tehran on the map

Tehran stretches along the foot of the Alborz Mountains in northern Iran. Snow and rain once fed the city’s key reservoirs, but climate change has reduced both.

Because of its geography:

Pollution gets stuck against the mountains.
Dependence on mountain dams leaves the city vulnerable in dry years.

Critical Thinking

4. Which City Is in Worse Shape?

The question is not simple. Both cities face real danger if water use does not change.

Tehran’s crisis feels more sudden. In very dry years, the dams can drop to crisis levels quickly.

Mexico City’s crisis is slower but deeper. As aquifers collapse and the city sinks, the natural “storage space” under the city is permanently reduced.

Some experts say Tehran is at greater risk right now. Others say Mexico City has the more permanent damage. Both viewpoints have truth.

Short Story – Level 4

5. Story: Two Friends and One Problem

Camila lives in Mexico City, a huge city high in the mountains. Every morning she turns on the tap and waits, hoping the water will come. Some days it arrives quickly, but other days only a slow, weak trickle slides out. Her mother reminds her to fill the rooftop tank whenever they can, because no one knows when the next shut-off will happen.

Far across the world, her friend Reza in Tehran is living a very similar routine. His family keeps large plastic bottles lined up along the kitchen wall, ready for the hours when the city sends water through the pipes. Many evenings, the pressure is too low to wash clothes, so his mother fills buckets while she cooks dinner. Reza has heard adults talk about the dams in the mountains above the city, the ones that are shrinking each year as rain and snow become less dependable.

One afternoon, Camila and Reza start messaging each other about their day. Camila explains that the ground under Mexico City is sinking because people have pumped too much water from the aquifers. Reza tells her that Tehran’s problem is in the mountains, where the reservoirs are so empty that the city fears running out. As they talk, they both realize something they had never thought about before: even in different countries, their futures depend on the same basic thing—water that people can count on.

By the end of their conversation, they both feel a little worried, but also more hopeful. They promise to take shorter showers and fix small leaks at home. They talk about telling friends at school what they learned. And although they live thousands of miles apart, they both end their chat the same way—hoping their cities will find smart, careful ways to protect the water that millions of people depend on every single day.

Teachers may ask: “What could Camila and Reza’s cities do to save more water?”