1. Unit 5 – Fresh and Salt Water Systems
Topic 1.1 The distribution of water on Earth

2. Earth
Our planets has more water than any other planet in our solar system
Our water exists in different forms unlike Mars where the water is all frozen

3. Drinking Water
Humans and other living things would die without drinkable water.
Drinking water has to be FRESH not SALT
Think about this:
Would you drink water that has formed in a puddle on the side of the road? What about water that has gathered from the rain in your back yard?
This is FRESH water, but it is not drinkable.
Water that humans can drink safely is called potable water

4. Let’s see what you think
Look at the circle on your page:
The circle represents how much water there is on Earth.
Color in how much water you think is potable water and how much is not.

5. Water on Earth
Of all the water on Earth, 97% is salt water and 3% is fresh water.
Of the fresh water:
77% is ice
22% is ground water
1% is in lakes, rivers and wetlands.
Most of the water that is actually fresh for us to drink is locked in ICE! Ahhh!

6. FYI
Of all the fresh water in the world, we can only get to 0.003% of the drinking water.

7. Topic 1.2 – Water Quality

8. Water Quality
When you turn on your tap, you expect your glass to fill up with clear water that has no unpleasant odor or taste….. Right?
Water quality describes how pure the water is.

9. Water in nature is NEVER EVER pure.
It always contains organisms, minerals and chemicals.
Have you ever heard of beaver fever?

10. Substances dissolved in water
Most of the substances dissolved in water are called salts.
The total amount of salts dissolved in water is called salinity
Did you know sea water has a lot of salt but also SILVER AND GOLD?

11. Did you know?
Over 1 billion people drink dirty water every day because they can’t get clean water
3 to 5 million people die each year from unsafe water
WE ARE QUITE LUCKY TO HAVE THE RESOURCES WE DO IN CANADA

12. Hard Water
As water flows, it dissolves minerals from the soil and rocks
Hard water contains a high concentration of the minerals calcium and magnesium.
If you have hard water in your house, you may notice that your soap when you wash doesn’t lather very well.

13. Hard water leaves mineral deposits on kettles, pipes, hot water heaters….

14. Organisms in drinking water
Some organisms in water can be quite harmful
Escherichia coli (also known as E. Coli) is a type of bacteria that can cause sickness and even death.
Our water treatment in Canada usually catches these bad organisms before the water gets to our homes.

15. Water testing criteria
1. Look at the water (color and cloudiness)
Remember: clear water is not always a sign of clean water
2. Smell the water

16. What is water tested for?
1. Taste and odor
2. Cloudiness and color
3. Toxic substances and other pollutants
4. Bacteria
5. Hardness or mineral content
6. pH (how acidic or basic the water is)
7. Floating solids
8. Dissolved solids

17. Can you change salt water to fresh water?
1. Distillation
2. Reverse Osmosis

18. Distillation
In distillation, the water is boiled so that the water evaporates and leaves the salt behind.
Liquid fresh water is then formed as condensation
WE ARE GOING TO TRY THIS TOMORROW!  We are going to try a solar still

19. Reverse Osmosis
Reverse osmosis works by forcing salt water through a filter
REMEMBER: Osmosis is the movement of water particles through a membrane. (from an area of high concentration to an area of low)
Reverse osmosis is just as it sounds. It moves water from an area of LOW concentration to an area of HIGH concentration.
This way the water leaves behind the salt