Q1

Several options exist for purification is with iodine. It is easy and effective in twenty minutes, but iodine should not be used long-term. In addition, pregnant women and people with thyroid should avoid purification with iodine. Two popular iodine treatments in the U.S. are Potable Aqua and Polar Pure. While iodine renders water bacteriologically safe, it doesn’t remove chemical contaminants. Many people dislike the taste of iodine-treated water.

A third method of water purification is with a small amount of household bleach. This will kill some but not all microorganisms. Again, many people dislike the resulting taste.

Filtering cleans water mechanically. According to Katatdyn, the makers of many travel water filters, a good microfiltration unit can remove: “harmful cocci, bacteria, protozoa, fungi, cysts, and parasites are totally removed, including the chemically resistant infectious agents of Giardia, the amoebic and shigella dysenteries and those causing typhoid, cholera bilharzia and a long list of other dangerous diseases.”

Filtration has the advantage that it does not require chemicals. While filters are the most expensive option, a good filter pumps out good water in a few minutes and is reusable.

Q2

The two most common desalination techniques are distillation and reverse osmosis. Both of these require energy to remove salts from seawater or brackish water, and thus inherently are expensive. If a less expensive option is available (such as hauling fresh water from a distance), then less expensive option is used.

Q3

a. The likely source of lead is from solder in the pipe joints or from lead pipes themselves.

b. Research activities should not contribute to lead in the drinking water, assuming that any lead compounds are disposed of using prescribed methods. Although many undergraduate chemistry experiments used to use lead, most now have been redesigned to avoid it and other toxic metal ions completely.

Q4

Only water-soluble vitamins would be expected to be polar molecules. Though a fat-soluble vitamin will often have individual polar bonds or small regions of the molecule, overall this is out-weighed by nonpolar sections. Polar covalent bonds attract to water through hydrogen bonding and may allow the molecules to dissolve in water, while nonpolar covalent bonds favour interactions with the nonpolar chains in lipids.