E. Earth and Space Systems · Water Systems

Fresh Water Scarcity: Impacts and a Plan of Action

E1.1 A1.3 A1.5 A3.2 A1.4About 60 minutes

Learning goals

I can explain physical and economic water scarcity.
I can assess the social and environmental impacts of fresh water scarcity, in Canada and around the world.
I can calculate and reduce my household's water use.
I can design, build and test a water-saving device and propose a plan of action for fresh water sustainability.

Words to know

water scarcity
Not having enough safe fresh water to meet the needs of people and nature in an area.

physical water scarcity
When there isn't enough water in a region, for example because of a dry climate or drought.

economic water scarcity
When water exists but people can't get it because of a lack of pipes, treatment, money or fair access.

drought
A long period of below-normal precipitation that causes water shortages.

sustainability
Meeting today's needs without harming the ability of future generations to meet theirs.

greywater
Lightly used water from sinks, showers and laundry (not toilets) that can sometimes be reused, for example to flush toilets.

plan of action
A step-by-step plan that says what will be done, by whom, by when, and how success will be measured.

Bringing the unit together

You've learned that fresh water that's easy to reach is a tiny part of Earth's water (Lesson 1), that it moves through watersheds and aquifers (Lessons 3 and 4), that melting ice and pollution are changing it (Lessons 5 and 8), and that how we treat, share and value water matters (Lessons 9 to 11). Now you'll put it all together to assess water scarcity and make a plan.

Day Zero

In early 2018, after three years of drought, Cape Town, South Africa, a city of millions, warned that its taps might be shut off on "Day Zero". People were limited to 50 litres per person per day for everything: drinking, cooking, washing and flushing. By saving water together, and with the return of rain, the city avoided Day Zero. How does 50 L compare with your day? In 2021, Canadians used an average of 223 litres per person per day at home (Statistics Canada).

A dry reservoir with a wide cracked mud bed and a small shrunken pool of water in the middle. — During a long drought a reservoir can shrink like this. This is physical water scarcity: not enough water in the region. AI-generated image

Two kinds of scarcity

Physical scarcity: not enough water in the region: deserts, droughts, over-pumped aquifers, rivers that run dry.
Economic scarcity: water exists, but people can't access it safely because of missing pipes, treatment, money or fair access. A community can be beside a huge lake and still lack safe tap water. Long-term drinking water advisories in some First Nations communities (Lesson 10) are an example of this kind of problem in Canada.

Around the world, about 2 billion people do not have safely managed drinking water at home (WHO and UNICEF).

Social impacts	Environmental impacts
Illness from unsafe water (such as diarrheal diseases)	Rivers, lakes and wetlands shrink or dry up
Time spent collecting water, often by women and girls, instead of school or work	Fish and wildlife lose habitat
Higher food prices when crops fail	Aquifers are over-pumped; the water table drops
Jobs lost in farming and industry	Land can sink when aquifers are drained
Conflict over who gets water; people forced to move	Salt water can push into coastal aquifers
Stress, unfairness and loss of culture where water is central to identity	More wildfires in dry forests

Some impacts of fresh water scarcity.

Can Canada have water scarcity?

Yes, locally. The Prairies have faced serious droughts that hurt farms and ranches. In Ontario, conservation authorities can declare low water conditions (Levels 1 to 3) under the Ontario Low Water Response program and ask people to cut water use. Some fast-growing communities depend on aquifers that have limits. And economic scarcity affects communities under long-term drinking water advisories. Climate change is expected to bring more extreme events: heavier rain at some times, longer dry spells at others.

Worked example

Let's calculate household water use

Estimate one person's daily indoor water use: an 8-minute shower with a showerhead that uses about 9.5 L per minute; 5 toilet flushes with an older toilet using 13 L per flush; 4 minutes of tap running while brushing teeth at 8 L per minute; plus 10 L for drinking, cooking and hand washing. Then calculate the savings from three changes: 5-minute showers, a 4.8 L toilet, and turning the tap off while brushing (using only 1 L).

Before: shower 8 × 9.5 = 76 L. Toilet 5 × 13 = 65 L. Brushing 4 × 8 = 32 L. Other 10 L.
Total before = 76 + 65 + 32 + 10 = 183 L.
After: shower 5 × 9.5 = 47.5 L. Toilet 5 × 4.8 = 24 L. Brushing 1 L. Other 10 L.
Total after = 47.5 + 24 + 1 + 10 = 82.5 L.
Savings = 183 − 82.5 = 100.5 L per day, a cut of about 100.5 ÷ 183 ≈ 55%.
Over a year: 100.5 × 365 ≈ 36 700 L, about 37 m³, for one person.

From about 183 L to about 82.5 L per day: a saving of about 100 L per day (about 55%) and roughly 37 000 L per year.

Water use in litres per person per day. The average Canadian at home in 2021 used about 4.5 times Cape Town's Day Zero limit; the lesson example shows how three simple changes cut daily use by more than half.

Just for fun

Shower karaoke tip: pick short songs. At 9.5 L per minute, a 6-minute rock ballad uses about 57 L, but a 3-minute pop song uses about 29 L. Your water bill gets a vote on the playlist.

Hands-on activity

Design challenge: a water-saving device (A1.3, A1.4)

Problem: houseplants and garden pots are often over-watered: water runs out the bottom and is wasted. Design, build and test a self-watering planter that uses less water.

Criteria: keeps soil damp (not soggy) for at least 5 days; wastes no water out the bottom; uses recycled materials. Constraints: a 2 L plastic bottle, cotton string or a strip of old cotton T-shirt, soil, a small plant or seeds, tape; build time under 1 hour.

Plan: sketch a design. (Common idea: a grown-up cuts the bottle in half; the top half is turned upside down into the bottom half like a funnel; a cotton wick runs from the soil in the top down into water in the bottom, so the plant draws up only what it needs.)
Build your prototype. A grown-up does all cutting with scissors or a craft knife and tapes any sharp edges.
Test: record how much water you add and how many days the soil stays damp. Compare with a normal pot watered on top with the same amount (measure any water that drains out).
Improve: try a thicker wick, a different soil, or a cover to reduce evaporation. Test again.
Communicate (A1.5): present your design, data and improvements in a short report or video.

What to look for: a clear design sketch, measured data from at least two tests, at least one improvement based on results, and a conclusion about water saved.

Safety (A1.4): only grown-ups cut plastic bottles; cover cut edges with tape; wash hands after handling soil.

A self-watering planter made from a plastic bottle (a grown-up does the cutting). The cotton wick draws water up into the soil as the soil dries, so no water drains out and is wasted.

Making a plan of action

A good plan answers: What is the problem? What will we do? Who will do it? By when? How will we measure success?

Levels of action:

Personal and household: shorter showers, fix leaks, full loads only, water gardens in the morning, collect rainwater, choose native plants that need less watering, never pour chemicals down drains.
School and community: water audits, rain gardens, stream clean-ups with the conservation authority, campaigns, storm drain marking.
Advocacy: write to a municipal councillor or MP or MPP about protecting wetlands and aquifers, fixing leaky mains, or supporting First Nations' calls for safe drinking water.
Global: support organizations working on safe water; learn about how the food and products we buy use water.

Your turn

What is the difference between physical and economic water scarcity?

What was "Day Zero" in Cape Town, and what limit did people live with?

How much water did Canadians use at home per person per day in 2021?

Name two social impacts and two environmental impacts of water scarcity.

Give three ways a household can save water.

What should every plan of action include?

Give an example of economic water scarcity in Canada.

More practice: warm-up

What is a drought?

What is greywater?

How many litres does a toilet that uses 4.8 L per flush use for 6 flushes?

How much water is in 1 m³?

What does sustainability mean?

More practice: on your own

A shower uses 9.5 L per minute. How much water does a family of 4 save in a week if each person cuts their daily shower from 10 to 6 minutes?

Compare Cape Town's 50 L limit with Canada's average 223 L. How many times more did the average Canadian use?

Why can water scarcity happen even in a country with lots of fresh water, like Canada?

Explain how water scarcity can affect girls' education in some countries.

In the design challenge, why should you compare your planter with a normal pot watered with the same amount?

Challenge

Write a SMART plan of action for your school (Specific, Measurable, Achievable, Relevant, Time-bound) to reduce water waste. Include at least three actions and how you would measure success.

Assess this claim: "If everyone in Ontario saved water at home, it would solve water scarcity around the world." Is it true? Explain.

Use at least three different lessons in this unit to explain why protecting a local wetland is part of a fresh water sustainability plan.

Check your understanding

Quiz

A community next to a large lake has no water treatment plant and must boil its water. This is an example of...

In 2021, Canadians used about how much water per person per day at home?

Which is an ENVIRONMENTAL impact of water scarcity?

An 8-minute shower at 9.5 L per minute uses...

Which part of a plan of action tells you whether it worked?

During the 2018 Cape Town crisis, people were limited to about...

For parents and teachers

Big idea (E1.1): fresh water scarcity can be physical or economic and has social impacts (health, education, food, jobs, conflict) and environmental impacts (dried-up wetlands, habitat loss, falling water tables). Students assess these and propose a plan of action. The planter is an engineering design process (A1.3) with safety (A1.4) and communication (A1.5); the water-use calculations connect to math (A3.2).

How to help: do a family water audit for one day using the example as a model. Help with the design challenge (adults do all cutting). Talk about one action your family will actually keep doing.

Common difficulties:

Thinking scarcity only happens in deserts. Economic scarcity happens near water too.
Plans that are too vague. Push for who, what, by when, and how to measure.
Climate worry. Emphasize that individual, community and government actions all help.

Safety: adults cut bottles; tape sharp edges.

Sources: Statistics Canada (223 L per person per day in 2021); City of Cape Town 2018 water restrictions (50 L per person per day); WHO/UNICEF Joint Monitoring Programme (about 2 billion people without safely managed drinking water); Ontario Low Water Response program. Showerhead and toilet flow rates in the example are typical values used for calculation.