Where Water Comes From
Fresh or salty? Sort the sources.
What this lesson covers
Why it matters
Rain, rivers, wells, the deep blue sea. Water is all around us, but only some of it is fresh enough to drink. Can you tell which is which?
Predict first
Which natural source gives the purest water?
Rain water is the purest natural water, because it forms from evaporation, which leaves salts and dirt behind. Sea water, in contrast, is full of dissolved salt.
- Sea water
- Rain water — correct
- Muddy pond water
- Water from a drain
What you do
Sort each water source into fresh water or salty (sea) water.
Check yourself
Which of these is the purest form of natural water?
Rain water is the purest natural water because it forms when water evaporates and leaves salts and impurities behind, then falls as rain.
Sea water is far too salty to drink. What must be done to make it drinkable?
Desalination means removing the salt from sea water. Only after the salt is taken out is sea water safe and pleasant to drink.
About how much of all the water on Earth is fresh water that we can actually use?
Most of Earth's water is salty sea water. Only about 1% is fresh water we can easily use, so we must not waste it.
- Rain water — correct
- River water
- Sea water
- Well water
- Desalinate it — remove the dissolved salt — correct
- Add more salt to balance it out
- Freeze it into ice cubes
- Simply pour it into a bottle
- Only about 1% — correct
- About 90%
- Exactly half
- None at all