Bottled Versus Tap Water: What You Drink and Why

Marie Villarba, Seattle Central Community College

Summary

This activity focuses students' attention on drinking bottled versus tap water, as well as bottled "enhanced water" or energy drinks like Gatorade, Powerade, and Vitaminwater, to address the "big idea" in chemistry of solutions and the sustainability "big ideas" of true-cost accounting and confronting over-consumption. This project is intended for students in any introductory-level chemistry course, for science majors (CHEM 139, CHEM 161) and non-science majors (CHEM 110, CHEM 121), to learn about the properties of solutions, acidity and pH, electrolytes versus non-electrolytes, and solution concentration. In the activity students explore: why they buy bottled water versus tap water; why they buy energy drinks and whether or not those reasons are valid; the cost to consumers for these products relative to the actual costs of ingredients in the drinks; and, the true cost of bottled beverages in terms of the life cycle of a plastic bottle. Hopefully, this activity will also dispel common misconceptions about tap water and bottled beverages.

Learning Goals

The goal is for students to grasp the "big idea" in chemistry of solutions; and the sustainability "big ideas" addressed by this activity are confronting and creating alternatives to over-consumption and true-cost accounting for bottled beverages.

Students will learn about: the properties of solutions; acidity and pH; electrolytes versus non-electrolytes; and, solution concentration.
In the activity students explore: why they buy bottled water versus tap water; why they buy energy drinks and whether or not those reasons are valid; the cost to consumers for these products relative to the actual costs of ingredients in the drinks; and, the true cost of bottled beverages in terms of the life cycle of a plastic bottle. Hopefully, this activity will also dispel common misconceptions about tap water and bottled beverages.

In the process of learning about the bottled water industry and energy drinks students should, hopefully, recognize they are often paying exorbitant amounts of money for well-marketed tap water and sugary salt solutions they could easily prepare at home for a fraction of the cost.

Context for Use

This project is intended for students in any introductory-level chemistry course, for science majors (CHEM 139, CHEM 161) and non-science majors (CHEM 110, CHEM 121), to learn about the properties of solutions, acidity and pH, electrolytes versus non-electrolytes, and solution concentration.

For most introductory chemistry courses (for non-science or allied health majors as well as preparatory chemistry), properties of solutions, electrolytes, acids and bases, and solution concentration are generally covered in the second half of the course. Because these topics are covered in the prerequisite course (typically AP or honors high school chemistry, CHEM 121 or CHEM 139), General Chemistry I students can easily carry out this experiment in the first few weeks of the course.

Outside the lab students will also carry out a taste test to determine how closely they could match the taste of each beverage. Finally, they will compare the cost of preparing the solutions using the basic ingredients (e.g. salt, sugar, citric acid, food coloring, etc) with the cost of each beverage.

Description and Teaching Materials

Students will also consider energy drinks and use the basic ingredients reported on the labels of three popular drinks (Gatorade, Powerade, and Vitaminwater) to prepare similar solutions in the laboratory. Students will then test the solutions for properties such as density, pH, and conductivity to explore properties of solutions, such as pH, acidity, electrolytes versus nonelectrolytes, and solution concentration. Outside the lab students will also carry out a taste test to determine how closely they could match the taste of each beverage. Finally, they will compare the cost of preparing the solutions using the basic ingredients (e.g. salt, sugar, citric acid, food coloring, etc) with the cost of each beverage.

Outside the lab students will also carry out a taste test to determine how closely they could match the taste of each beverage. Finally, they will compare the cost of preparing the solutions using the basic ingredients (e.g. salt, sugar, citric acid, food coloring, etc) with the cost of each beverage.

The Learning Activities

This activity includes several parts, including a survey, in-class group discussion, taste tests, and a laboratory experiment.

In a homework assignment, students complete a survey regarding their preference and their reasons for drinking bottled versus tap water and if and why they buy energy drinks. Students also calculate their annual cost of bottled water and determine the equivalent cost of drinking tap water, as well as the cost of any energy drinks. During the next class meeting students view the 7-minute "20/20" video segment on "Bottled Water versus Tap" to dispel any misconceptions. Next, in small groups of 3-4 students discuss their responses on their survey, what they observed in the video, if the video changes any of their views regarding bottled and tap water. After 10-15 minutes one member from each group reports out to the class. Students may also want to carry out a blind taste test where the most common types of bottled water are included as well as tap water from the school or their homes. This activity may be carried out during a 50-minute class period or as an activity preceding the wet-lab component in the lab-of course, the taste-test component must be done outside the lab. This activity can easily be done in any course or even as an activity for a student organization, such as a sustainability club.

In the wet-lab experiment, students will use the amounts of sodium, potassium, sucrose, citric acid, and other ingredients reported on the labels of each Gatorade, Powerade, and Vitaminwater to prepare similar solutions in the laboratory. They will use density to determine the approximate mass of dissolved substances in the beverage and pH meters or pH paper to determine the relative acidity. Students will try to reproduce each beverage using sodium chloride, potassium chloride, table sugar (for sucrose), honey (for fructose and glucose), and lemon juice (for citric acid). These substances will also allow students to study the differences between electrolytes and non-electrolytes using voltmeters. Outside the lab students will carry out a taste test to determine how closely they can match the taste of each beverage. Finally, students will calculate the cost of the ingredients used to reproduce each drink and compare that cost to the cost of the brand-name drink. Students should be able to complete this experiment in about two hours.

During the next few class meetings, students should be able to prepare the solutions and carry out the taste tests. They can also view the two-minute "HowStuffWorks: Vitaminwater" video. Afterward, students can discuss the cost of energy drinks and whether "enhanced water" drinks are worth the money or if they are simply marketing gimmicks. In addition, the documentary "Flow" can also be viewed, so students can learn more about the bottled water industry. The preparation of comparable sports drinks, taste tests, videos, and discussions can be carried out during a lab period and several 50-minute class periods.

Water Survey (Microsoft Word 30kB Nov1 11)
"Analyzing Sports Drinks" Wet-lab Experiment (Microsoft Word 157kB Nov1 11)

Teaching Notes and Tips

Assessment

Formal assessments will be carried out for the calculations related to the activity, specifically those carried out for the laboratory component, like molar concentration of ions in solution. In addition, students will be assessed on their ability to correctly identify which solutes used for the "energy" drinks are electrolytes or non-electrolytes based on conductivity tests and to write the relevant dissociation reactions occurring for each electrolyte. Students will also be assessed on their ability to identify each solute added as acidic, basic, or neutral based on pH measurements and to write the relevant hydrolysis reactions for each.

Students will also be assessed on their ability to support their views regarding bottled water and energy drinks given the videos viewed, the taste tests carried out, their experiences in lab, and other resources provided.

References and Resources

WEBSITES ON BOTTLED WATER versus TAP WATER

Bottled Water vs Tap Water on 20/20 video (7:31)
http://www.youtube.com/watch?v=_3QBZac3MSY&feature=related
http://abcnews.go.com/2020/Health/Story?id=728070&page=1
http://abcnews.go.com/print?id=728070

Penn & Teller's Showtime Series "Bull$#!+: The Truth About Bottled Water" (video 12:45) - contains profanity.
http://www.youtube.com/watch?v=XfPAjUvvnIc

CNN: Most Bottled Water is Tap video (2:30)
http://www.youtube.com/watch?v=saSgpX186MM

WEBSITES ON BOTTLED WATER

Bottled Water on the National Resources Defense Council (NRDC) Website
http://www.nrdc.org/water/drinking/qbw.asp#safer

Bottled Water Consumption by Country (1997-2004)
http://www.worldwater.org/data20062007/Table10.pdf

Bottled Water Consumption per capita by Country (1999-2004)
http://www.earth-policy.org/plan_b_updates/2006/update51

WEBSITES ON BOTTLED ENHANCED WATER AND ENERGY DRINKS

How Stuff Works: Vitaminwater video (2:03)
http://recipes.howstuffworks.com/vitaminwater.htm

Gatorade Wiki
http://en.wikipedia.org/wiki/Gatorade

Powerade Wiki
http://en.wikipedia.org/wiki/Powerade

WEBSITES ON TAP WATER

HowStuffWorks Show: Episode 4: Poisonous Water [sewer to tap] video (2:38)
http://videos.howstuffworks.com/discovery/31881-howstuffworks-show-episode-4-poisonous-water-video.htm

American Dental Association (ADA): About Fluoridation Facts
http://www.ada.org/4378.aspx

ADA Fluoridation Facts: The 71-page booklet is a comprehensive encyclopedia of fluoridation facts taken from over 350 scientific references (read-only PDF file)
http://www.ada.org/sections/professionalResources/pdfs/fluoridation_facts.pdf

WEBSITES ON PLASTIC BOTTLES and OVERCONSUMPTION

How It's Made: Plastic Bottles video (4:50)
http://www.youtube.com/watch?v=T01i_vp2mJE

Facts about Plastic Bottles
http://earth911.com/news/2010/05/24/the-numbers-on-plastics/

How Bottled Water Works: Controversy: Ecological Effects
http://recipes.howstuffworks.com/bottled-water4.htm

WEBSITE ON OVERCONSUMPTION

Seattle Artist Chris Jordan
http://www.chrisjordan.com

Traveling Exhibitions of his works, September, 2009 - January, 2010 - Pacific Science Center, Seattle

Evergreen State College