Consider This 5.3 Finding Out About Bottled Water
If you search for "bottled water" on the Web, you will get over five million hits. Select two sites to explore, one provided by a supplier and the other provided as a source of consumer information. The former may flood you with statistics about the benefits of bottled water; the latter may raise questions, such as "Is bottled water safer?" or "Is it worth the cost?" For each site, list the title, source, URL, and two things that you learned about bottled water. Consider This 5.4 Your Home's Water Source
When you turn on the tap at home, where does your drinking water come from? You can find out by using the Safe Drinking Water Information System (SDWIS) of the EPA. Determine the source of your home's water by clicking on your state and county/community, and then answer these questions.
a. What is the name of the water system that services your home?
b. What is the primary water source for that system?
c. What information from the past 5 years is given about the quality of that system's drinking water? |
Sceptical Chymist 5.8 Bottled Water and Claims of Purity
The Web site for Penta Ultra Premium Purified Drinking Water states:
"Penta ultra-premium purified drinking water is the cleanest-known bottled water."
Consider some other claims made by the company about their product.
As a Sceptical Chymist, evaluate each of these claims. Be sure to explain your reasoning. Consider This 5.25 - Three-Dimensional Representations of Molecules
Specific structural features of molecules often are more readily apparent if you look at their three-dimensional representations. Here are rotatable images of ethanol, ethylene glycol, and sucrose. Identify the regions in each molecule where hydrogen bonding can occur. Has your mental picture of these molecules changed after seeing these 3-D representations? Explain. Browse through some other molecules from this list and identify several others that could participate in hydrogen bonding. Hint: click and drag with your left mouse button over the image to rotate. |
Consider This 5.26 A Drink of Water – What is in it?
Table 5.11 is merely a starting point for the wealth of information available about six possible pollutants in drinking water. At the EPA Office of Ground Water and Drinking Water, you can access a consumer fact sheet on each of these pollutants, as well as dozens more. A consumer version and a technical version are available, and the latter is recommended. Look up a pollutant listed in Table 5.11 to find out how the pollutant gets into the water supply and how you would know if it were in your drinking water. Is your state listed as one of the top states that releases the contaminant? Note: Arsenic, cadmium, lead, chromium, mercury, and nitrate/nitrite ions are found under the section on Inorganic Contaminants. Benzene is listed under Volatile Organic Contaminants. No trihalomethanes such as CHCl3 currently are listed, but you can find a variety of other chlorinated compounds found in water, such as CCl4 and CH2Cl2. Consider This 5.27 Water Emergency Relief
In 2006, at the 231st national meeting of the American Chemical Society in Atlanta , Georgia , a great buzz of excitement surrounded a new, tiny water purification system. Called PUR Purifier of Water, the chemical systems are made by Proctor and Gamble. Producing clean water that rivals what you would get from a modern treatment facility, 40 million of the small packets were distributed world-wide for sustained water remediation and emergency relief. Able to remove toxic metals, pesticides, and deadly pathogens, the chemical filters the size of a ketchup packet are inexpensive also. Use the Web to see if the water purifiers have lived up to their hype. Write a short report detailing their contents and effectiveness, and describe situations where they have proven useful, if at all. |
Consider This 5.28 Cryptosporidium
As of January 1, 2002 , EPA's surface water treatment rules require systems using surface water or groundwater under the direct influence of surface water to remove or deactivate 99% of Cryptosporidium. - What is Cryptosporidium ?
- What are the sources of this contaminant in drinking water?
- What are the potential health effects from drinking water contaminated with cryptosporidium?
- Why was this rule issued in 2000, but not required until 2002 for large systems (those serving more than 10,000 customers?
- For systems serving fewer than 10,000 customers, when does this rule take effect?
Consider This 5.29 Oops… It Happened Again
Community water fluoridation was cited as one of 10 great public health achievements of the 20 th century by the Centers for Disease Control and Prevention (CDC). In 2005 the American Dental Association celebrated " 60 years of community water fluoridation." But in 2006, the American Academies of Science published a report (read excerpts here) claiming that this practice can damage bones and teeth, and that Federal standards may put children at risk. Who is to be believed? Use the resources of the Web to help settle this controversy. Perhaps the class could use this topic for a lively debate. |
Consider This 5.30 Lead, Mercury, or Cadmium
Find out whether lead, mercury, or cadmium ions are a significant problem in drinking water where you live or on your campus. For many communities, data can be located with this map of local drinking water systems provided by EPA's Office of Ground Water and Drinking Water. Your local water utility company or state drinking water program should be able to provide information as well. - If these ions are present, what are some likely sources of them?
- Are the concentrations of these ions above the MCLG or MCL values? Compare the values reported for your water with the values in Table 5.11.
Consider This 5.32 Regulating Arsenic in Drinking Water
Another toxic metal that can find its way into public water supplies is arsenic. Early in January 2001, the Clinton administration issued a 10-ppb standard for arsenic in drinking water, replacing the standard of 50 ppb set in 1962. The Bush administration soon after recalled the rule before it could take effect, thus reverting to the 50 ppb standard, a controversial decision. - What was the reasoning behind each administration's decision?
- What has been the response to each administration's decision?
- Determine whether the 50 ppb is still the standard for arsenic.
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Consider This 5.36 Water from the Sun
Solar-powered reverse osmosis desalination units providing 400 liters of water per day were developed at Murdoch University in Perth, Australia. Twenty-five units are now in operation in Australia and Asia. Larger units providing 15,000 L/day are being tested. Use the Web to find other examples where potable water is being produced using the power of our nearest star. Be prepared to present your findings to your class. |
