Name:
Period:
Los Angeles Water Crisis: Where’s the Water?
Water Filtration Activity
OBJECTIVE
Learn about the Los Angeles water shortage and ways to reduce its effects. Assemble a water filtration
tower and test its ability to purify two different types of contaminated water: a dirty water mixture and
a salt water solution. Relate the results back to methods of improving the LA water shortage problem.
MATERIALS
4 x Filter containers (2 x 6 open holes, 1 x 4 open holes, 1 x 2 open holes)
4 x 250 mL beakers (transparent)
1 x Filter paper sheet
Sand
Active carbon
Cooking oil
Table salt
Microscope
Gravel
Soil
Electricity meter
PRE-ACTIVITY QUESTIONS
1. What types and sizes of contaminant do each type of filter material separate?
- Gravel
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Sand
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Active carbon
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Filter paper
2. Which filter material do you think will be most effective in separating out soil? How about oil?
How about salt? Why?
3. Is our filter tower an example of PASSIVE or ACTIVE filtration? Why?
Name:
Period:
PROCEDURE 1: Dirty Water Filtration (Day 1)
Member 1: Prepare the filter components
1. Place the gravel, sand, and active carbon in the three 250 mL transparent beakers.
2. Rinse each filter material with water. Drain the water from the filter material. DO NOT POUR
MATERIAL OUT OF BEAKER WITH THE WATER!
3. Rinse each filter container with water. Clear of any debris left over from previous filtrations.
4. Give the filter materials to Members 3 and 4
5. Clean each of the 250 mL beakers and give to Member 2.
Member 2: Prepare the water solutions
1. In a clean 250 mL beaker, put 1 teaspoon of soil, 1 teaspoon of oil, and 30 mL of water and mix.
Members 3 and 4: Building the filter tower
1.
2.
3.
4.
5.
The two filter containers with 6 open holes contain gravel and paper filter.
The one filter container with 4 open holes contains sand.
The one filter container with 2 open holes contains active carbon.
Fill the appropriate container approximately half way with the correct filter material.
Place the filter containers on top of one another in this order (bottom to top):
1. Gravel
2. Sand
3. Active carbon
4. Filter paper
Whole Group: Filter the water
1. Examine the dirty water under a microscope. List any observations about the water’s
appearance, contents, etc (BE SPECIFIC!).
2. Place the filter tower onto a clean 250 mL beaker.
3. Pour the dirty water solution slowly into the top container of the filter.
4. List your observations about the change in the water’s appearance after it is filtered.
Name:
Period:
PROCEDURE 2: Salt Water Filtration (Day 2)
Members 1 and 2: Assemble filter tower as before (see previous page)
Member 3 and 4: Prepare salt water solution
1. In a clean 250 mL beaker, put 5 teaspoons of salt and 30 mL of water. Mix the solution.
2. Check the conductivity of the salt solution using your electricity meter. Did the bulb illuminate?
How bright is the bulb?
Whole Group: Filter the water
1. Examine the salt water solution under a microscope. List any observations about the water’s
appearance, contents, etc (BE SPECIFIC!).
2. Place the filter tower onto a clean 250 mL beaker.
3. Pour the salt water solution slowly into the top container of the filter.
4. Check the conductivity of the filtered salt water solution as before. List your observations of the
light bulb’s brightness. How does it compare to the unfiltered salt water solution?
5. List your observations about the change in the water’s appearance after it is filtered.
Name:
Period:
DRAWING CONCLUSIONS (individual; group discussion; class discussion)
1. How effective was the filter tower at purifying the dirty water solution? Be specific in your
discussion of your observations.
2. How effective was the filter tower at purifying the salt water solution? Be specific in your
discussion of your observations.
3. What elements of the filter tower were most effective at capturing the water contaminants
(soil, oil, salt)? Why?
4. Which contaminated water solution was the filter tower better at purifying (dirty or salt)?
Why do you think that is (based on the filter materials in the filter tower)?
5. Based on your experience with the filtration tower, how would you suggest reducing the
problems of water shortage in Los Angeles?
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What kinds of water sources would you focus on purifying?
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Would you focus on active or passive filtration? Why?