Main idea

People use water for drinking, cooking, bathing, flushing the toilet, laundry, washing cars, and watering lawns. Factories, farms, stores, public utilities, and homes use millions of litres of water daily. It is a big task for drinking water treatment plants to supply clean drinkable water to a town, city, or community, in particular if the water to be treated stems from surface water and not from groundwater. After we use it, drinking water becomes wastewater and goes into pipes to a sewer, which leads to a wastewater treatment plant and, once cleaned, it is discharged into a river, lake, or a sea. On the countryside, where there is no sewage system, the wastewater may be collected in a septic tank or constructed wetland. When used water ends up in nature and becomes a part of a natural water cycle, the man-made cycle is completed.

Goal

To present the man-made water cycle and to relate it to the natural (hydrologic) water cycle.

Concepts

use of water, water disposal → man-made water cycle → water resource, drinking water treatment, distribution system, use of water, wastewater, sewer, wastewater treatment plant;

Introduction: We Need Water, we Get Rid of Water

Discuss with pupils the man-made water cycle and try to find out all its elements:

  • How does drinking water get to your house? (It is piped from the groundwater or the river to the treatment plant, to a reservoir or storage tank, then to your home.)
  • How does water get to your school? (the same process)
  • What happens to water when it leaves your home or school? (It goes to a sewer system that leads it to a wastewater treatment plant, then it is discharged back to the river or lake.)
  • Where do people who do not live near a river or lake and do not have access to a city water distribution system, get their water? (wells) Where does wastewater from homes not connected to a sewer system go? (septic systems, or discharged directly into a river or lake)

Activities in this lesson

Man-made water cycle
4.1.1
Subject: Art and craft, Biology, Chemistry, Geography, Social skills
Age group: All, 4 - 6, 7 - 9, 10 - 12, 13 and up
Type of activity: Debate, Contest
Number of participants: Individual, Team
Where is the possibility of pollution hiding?
4.1.2
Subject: Art and craft, Biology, Chemistry, Geography, Social skills
Age group: All, 4 - 6, 7 - 9, 10 - 12, 13 and up
Type of activity: Debate, Project
Number of participants: Individual, Team

Discussion: Man-made Water Cycle vs. Hydrologic Water Cycle

Compare the man-made (anthropogenic) water cycle with the natural water (hydrologic) cycle. (In the man-made water cycle, the water comes from a lake or a river, it is distributed throughout the community, then goes to a wastewater treatment plant and back to the river. The hydrologic cycle is the movement of water from the atmosphere to the earth, from which it returns to the atmosphere again. Both cycles are continuous.)

  • What are the similarities? (Both cycles are continuous.)
  • What are the differences? (Humans produce excess waste, while in nature production and decomposition are in equilibrium. In nature, water is cleaned through natural processes, while in a man-made water cycle the wastewater treatment is still often missing in some countries, but this lack should be corrected.)