12.8: Water—Plain and Bottled

Plain drinking water from the tap isn’t so plain. As we have seen, water is a superb solvent, so depending on where it’s been, substances of all kinds dissolve in it. Even rain water falling through clear air collects various gases before it hits the ground. The dissolved substances are what give various waters their distinctive tastes—and sometimes odors and colors—and are what determine whether or not the water is safe to drink.

Although our senses separate the good-tasting from the bad, they don’t necessarily tell us which water is safe and which isn’t. For example, drinking water rich in iron tastes and smells bad, but iron is safe to drink. But lead in the drinking water, even at toxic levels, is tasteless and odorless.

For the nation as a whole, lead is the pollutant of most concern in the drinking water. The developing nervous system is particularly vulnerable to the toxic effects of lead. Thus, lead exposure is most worrisome among pregnant women and young children—population groups that also tend to be low in iron and calcium. Diets rich in iron and calcium can lessen the amount of lead absorbed.

Progress is being made in reducing this source of lead. The amount of lead allowable in drinking water has been lowered, and water suppliers are required to notify customers of any lead in the water. Also, current safety regulations ban lead pipes in new plumbing to be used for drinking water. Homes more than 100 years old might still have lead pipes, which should be replaced.

Lead solder on pipes is less serious (but more widespread), especially if the solder is more than 5 years old (lead solder dissolves more easily during the first 5 years). If your household plumbing is suspect, the water can be tested, and local water departments usually offer advice and help.

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From 2007-2010, about 2.6% of U.S. children ages 1-5 had blood-lead levels of more than 50 ppb. Even levels below this can cause cognitive and behavioral problems; no safe level of lead has been established.4 Environmental sources of lead include lead in housing, soil, water, and consumer products. Children often ingest flakes or dust from old peeling lead-based paint (directly or through contamination of other things they put in their mouth).

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Despite the variations in tap water throughout the country, most drinking water from the tap is safe, especially when the water comes from large municipal water systems. Any lead contamination generally comes from the lead in plumbing. Other hazardous contaminants tend to be localized (e.g., water from wells in certain areas).

Another aspect of drinking water to consider is its fluoride content and whether the water is “hard” or “soft.” Fluoride is found naturally in water and hardens the enamel of developing teeth, making the teeth highly resistant to tooth decay. (Fluoride in the drinking water also may possibly strengthen bones, offering some protection against osteoporosis.)

The optimum level of fluoride is about 0.7 ppm (0.7 part fluoride per million parts of water), a level which protects against tooth decay but isn’t enough to produce [harmless] mottled tooth enamel. Some water supplies naturally have more (and some fluoride can be removed); other water supplies need added fluoride to reach this level.

Whether water is “hard” or “soft” depends on its content of calcium, magnesium, and sodium. Hard water is relatively high in calcium and magnesium, and low in sodium, whereas soft water is relatively high in sodium and low in calcium and magnesium. Unlike soft water, hard water leaves behind a hard [mineral] “scum” or deposit in the automatic coffee maker, bathtub, etc., and interferes with the action of various soaps. Soap doesn’t “suds up” as well in the shower or dishpan, and hard water “grays” the white laundry.

So, many households prefer soft water. Some households install a water-softening apparatus to convert hard water into soft water (the apparatus exchanges the calcium and magnesium in the hard water for sodium). But because soft water is higher in sodium, this can be a concern for those on sodium-restricted diets. Also, soft water is slightly acidic, making it somewhat corrosive. (If there’s lead in the plumbing more of it will dissolve in soft water than in hard water.) A compromise is to soften only the hot water supply, and use only the cold (hard) water for drinking and cooking.

Bottled water is exceedingly popular. There’s a large variety—flavored or unflavored, with or without minerals, carbonated or not. Although many people drink bottled water simply because they like the taste, many drink it because they perceive it as more healthful than tap water. This perception is certainly valid if the tap water is harmfully contaminated, but this isn’t usually the case.

If your tap water doesn’t meet the standards of the Environmental Protection Agency (EPA), the water company is required both to notify you and to clean it up. The standards set for bottled water aren’t necessarily higher than for tap water, and most of the bottled water sold in the United States is in fact processed tap water.

Besides the added cost, an argument against bottled water is environmental, e.g., energy and pollution costs of bottling and transporting the bottles. Also, bottles that aren’t recycled contribute to the plastic debris that litter our land and sea.

Bottled water sometimes can be less healthful than tap water. Some, for example, are comparatively high in sodium. The various types and brands of bottled water can be confusing to the consumer. Although the brands vary and the types overlap, a few generalizations can be made:

Distilled water: Water is evaporated to steam, and the steam is condensed to make distilled water. Thus, the solid, mineral matter (including sodium) is left behind. (The distillation process doesn’t, however, remove all organic chemicals.) Since minerals give water their taste, distilled water tastes flat.

Mineral water: Water that contains minerals— which includes virtually all water except distilled water. Most bottled mineral water is, however, taken from a spring, and afterwards the mineral content of the water may or may not have been altered. When it’s called “natural mineral water,” its mineral content hasn’t been altered.

Spring water: Simply water that comes from a spring. It may or may not have been processed and, as ground water, it may or may not be contaminated. “Natural spring water,” means that it hasn’t been processed before bottling.

Sparkling water: Water that’s naturally or artificially carbonated. It tends to be relatively high in sodium.

Seltzer: Usually tap water that has been filtered and carbonated. Often, flavors are added, and sometimes sugar is added as well.

Club soda: Like seltzer, usually tap water that’s been filtered and carbonated. But unlike seltzer, minerals (usually including sodium) are added.