Can We Drink It?
Lesson Overview
Goals
- Describe contaminants that might be present in rainwater
- Describe how rainwater can be filtered and treated for consumption
Outcomes
Teaching Primer
As aquifers and other primary sources for drinking water continue to be reduced under the pressure of increased population demand, rainwater will become more attractive as a source of potentially potable water. Rainwater can contain a number of contaminants including bacteria, suspended solids, and heavy metals that find their way into the water as it moves through the system. This includes environmental toxins in the air or bird feces on the roof. It goes without saying that removing these nasties is a must.
Home filtration and treatment systems are being used in other countries for non-potable uses like laundry and irrigation. But the science is certainly there for a full potable water treatment system that integrates directly with the conveyance system from the roof.
And how great would that be?! Rain hits the roof, solids like leaves and sticks are screened out, and the water moves down the spouts and into a filtration and purification system. You go to your sink, turn it on, and out comes filtered and purified rainwater. Now that’s how Mother Nature intended it, don’t you think?
Teach the Teacher
Tools & Materials
- 2 liter bottle
- Knife
- Sand
- Pebbles
- Activated charcoal
- Cheesecloth or coffee filter
- Rainwater
Vocabulary
- Screening
- Filtering
- Disinfecting
- Purifying
Method
Introduction (10 minutes)
Begin this lesson by describing the process that rainwater would need to go through in order to be potable. Explain each of the filtration and purification methods.
Activity (20 minutes)
As a class, build a bio-filter to filter rainwater. Follow the instructions in the DIY Water Filter article to create the bio-filter. Once the filter is constructed, pull some rainwater from the rainwater storage system and ask the Students to inspect it for visible solids and contaminants. They may see debris from plants or the roof system.Then slowly pour the water into the filter. It may take a few minutes for the water to migrate through the various filter agents. Collect the filtered water and have the Students compare it with the unfiltered rainwater.
Discussion (5 minutes)
What were the visible differences between the rainwater and filtered water? Does it look cleaner? Do you think there are contaminants that were filtered out that we cannot see?
Assessment (10 minutes)
Use the following questions to assess the Students before and after the lesson. Tally the responses of the group in the Assessment Tracking Log for comparison:
- By a show of hands, how many of you think you can tell if water is safe to drink just by looking at it?
- Now that you know more about invisible contaminants like bacteria, how many of you think you could build a bio-filter at home with your parents?
Related Lessons
Give the Intermediate or Advanced lessons a try now that you’ve completed the Beginner Lesson!
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