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Public Drinking Water Treatment Process Explained

Learning Experience 4

Big Ideas

In most places in the world today, even water from a relatively clean natural source probably needs to be cleaned and tested before it can be consumed.

In Philadelphia, drinking water treatment is a multi-step process that in many cases mimics nature but also is tested every step of the way to comply with  federal regulations and ensure public health.

Summary

Making safe and reliable tap water requires a multi-step treatment process. Modeling one of the very important steps to clean water in class will help students see the evidence for themselves.

Engage

Start the class by holding up in front of your students two two clear glasses, one filled with tap water and one with rain water. 

Ask them:  Can I drink this water?  How do you know you can trust it to be safe to drink? 

Follow this with the slide deck questions to define the differences POTABLE, GRAY and POLLUTED and discuss the distinctions. 

POTABLE (Safe for human consumption)

GRAY (rain water for watering plants, washing sidewalks/cars/animals etc)

POLLUTED (not good for anybody or anything!)

Ask student to write a reflection.

Explore and Explain

Cleaning up polluted water activity. Gather the materials you need found in the MATERIALS tab and here  (Activity Worksheet (Including set up directions) for student instructions and to record their observations.

Note that this is a filtration activity similar in concept to PWD’s filtration step of drinking water treatment but simplified for the classroom.

Elaborate

In this next part of the Learning Experience, students will learn the steps in the Philadelphia Drinking Water Treatment System by watching a video, and seeing if they can put the steps in order from a card set you will prepare from this Drinking Water Treatment Poster. Record those steps in their notebooks or as a foldable.  Finally, ask them if any of the steps could be eliminated and why (or why not!)

If you want to share a striking example of how polluted our waterways were as a consequence of the industry and manufacturing  before federal regulation, share this newspaper story about Frankford Creek (this is only one article of many about how polluted the rivers were in the early to mid 20th century )    These pictures and letters from Philly H20: A Sad History of Frankford Creek  depict the issue from 1938.  Also here as a one-page format: Attachment 2.4-D

In modern times, the headwaters of the Schuylkill River are discolored by abandoned coal mine drainage

Extensions

COMPARE TO OTHER REGIONS NEAR PHILADELPHIA

Compare the Philadelphia Water Department Drinking Water Treatment process to other treatment processes. Consider differences in the way they treat the water, influences of geography, population, water supply, industry.  See Attachment 2.4-F for descriptions of the drinking water treatment process in Wilmington, Reading and Delaware as an example.

COMPARE TO OTHER CITIES

Describe the key factors that influence the designs of the drinking water treatment processes in Philadelphia and Las Vegas.

Teacher Support

Essential Question:
What does it take for us to drink a glass of fresh, clean, delicious water?

Guiding Questions:

Engage:

How do we know water is safe to drink?

Explore and Explain:

Can we convert our polluted water to gray water through filtration?
How can we model water filtration the way nature does it?
Is filtration enough to make water potable?

Elaborate:

What other steps are needed to make water potable?
What does each step do in the process?

Extension:

What are the components of water before it is treated that might be of concern to PWD and the public?

What are the key factors that influence the designs of the drinking water treatment processes in Philadelphia and Las Vegas?

Students will be able to:

Engage:

Differentiate between potable, gray, waste water and polluted water by recording reflections, ideas, and surprises in their Watershed Journal.

Explore and Explain:

Build a model of a water filtration system in order to “make the polluted water sample useable as gray water.”

Elaborate:

Describe the basic steps of our local drinking water treatment process (from gray water to potable water).
Argue to defend the importance of every step of the drinking water treatment process.
Describe the key factors that influence the designs of the drinking water treatment processes in Philadelphia and another city of their choice.

Explore and Explain

For groups of 3-4 students will need

Activity Worksheet (it has set up directions too)

“Dirty” water sample (prepared by the teacher ahead of time).

Mix soil, oil, food coloring, leaves and water in a large beaker. Note: If food coloring is used, students will not be able to filter out the food coloring which will lead to a connection to the issues surrounding dye factories and to connections explaining why filtering alone is not sufficient.
Plastic spoon/spatula
Funnels
Sand and gravel
Screens
100 mL, 250 mL beakers
Graduated cylinder (Note: the graduated cylinder gives the most accurate volume reading)

When cleaning up, make sure that oil and solids do not go down the drain!

Elaborate 

Drinking Water Treatment Process (VIMEO)

Drinking Water Process Poster (cut into the 8 steps and mixed up)

Newspaper clippings about Frankford Creek (Purple and Perfumed)

or as a link to HistoryPHLFrankford Creek Purple and Perfumed

Extension
Articles about different municipalities (Attachment 2.4-F)
Guinea Worm- TFK article (Attachment 2.4-G)

BASIC WORDS:
Coagulation noun
The process of changing from a liquid to a semi-solid state. (Chemicals are added to the water to bind smaller particles together to encourage them to settle).

Disinfection noun
The process of introducing a chemical or other product added to kill disease causing organisms.

Filtration noun
The act of capturing impurities from the water as it passes through a layer of sand, gravel and charcoal now called rapid sand filtration. Philadelphia first introduced a slow sand filtration process in the early 1900s using sand and gravel only.

Filtered water noun
Water that has undergone a process to make it cleaner and safe to drink

Flocculation noun
The formation of small clumps. (In this process, water is gently mixed to make sure that the chemicals added in coagulation have bonded and that particles combine to form “floc” which will settle).

Raw Water noun
The natural water found in the environment, such as rainwater, ground water, and water from bodies like lakes and rivers.

Sedimentation noun
The process of matter settling to the bottom of a liquid by gravity.

Source Water noun
The water from streams, lakes or underground aquifers that is used for drinking.

Tap Water noun
Water that is supplied to a tap. Its uses include drinking, washing, cooking, and the flushing of toilets.

Unfiltered Water noun
raw water

Wastewater noun
Water that comes from flushed toilets, sewers and manufacturing plants that needs to be treated before it enters our waterways

Students will differentiate between potable water, gray water, waste water and polluted water by recording reflections, ideas, and surprises in their Watershed Journal.

Students will build a model of a water filtration system in order to “make the water sample useable as gray water.”

In their Watershed Journal,/foldables, students can write a journal entry that describes all 8 steps to the local drinking water filtration process works. Include illustrations.

Each student will individually write an argument for NOT eliminating the step they studied.

PA STEELS

Environmental Literacy and Sustainability
3.4.6-8.G Sustainability and Stewardship: Obtain and communicate information to describe how best resource management practices and environmental laws are designed to achieve environmental sustainability.

Related Standards

EfS C.27 The Dynamics of Systems and Change – Track existing causal relationships (feedback loops) within the system over time.

ELA W.6 Write arguments to support claims with clear reasons and relevant evidence.

Student Materials

Student Worksheet

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