Last year, Americans were outraged when the price of gasoline topped $4 a gallon. Yet while they seethed at these record-breaking costs, few stopped to consider they were paying for an even more valuable liquid: water. 

At the bargain price of $0.00002 per ounce, tap water is basically free. So why do Americans continue to throw away $1.50 or more for a single-serve 16-ounce bottle of water - roughly 1,000 to 4,000 times the cost of tap water, according to USA Today. 

Priced by the gallon, Americans are spending around $12 on bottled water - more than three times the price of gasoline at its highest in 2008. Not only is this indulgence hurting their wallets, but it's also destroying the environment. 

Water bottles are made from polyethylene terephalate, a highly durable form of plastic produced from petroleum - the same fossil fuel used to make gasoline. Petroleum is integral to the entire bottling process, first as an ingredient to make the plastic bottles, then as an energy source to fill the bottles with water, carry them through the factories and distribute them around the world. 

Petroleum is not the only resource consumed during the bottling process: fresh water is too. It takes nearly 72 billion gallons of water, worldwide, to make a year's supply of empty plastic bottles. Upwards of one liter more is wasted during the filtering and purifying process. This means that for every liter of water consumed, at least two liters of water were required to produce it, according to a recent article in Reader's Digest. 

Some of the environmental toll could be alleviated through recycling. Because plastic bottles are made almost exclusively from petroleum, they are easier to breakdown than other plastics that contain aluminum and glass particles. As such, plastic bottles are highly desirable to recyclers. However, more and more bottles are finding their way into trashcans rather than recycling bins. 

If water and soft drink bottlers had used 10 percent recycled plastic materials in 2004, they would have saved the equivalent of 72 million gallons of gasoline. If they had used 25 percent recycled materials, Readers Digest reports, they would have saved enough energy to electrify more than 680,000 homes for a year. 

Unfortunately, even worse than failing to recycle water bottles is to reuse them. The truth is, the plastic bottles are designed for only one use. If consumers reuse the bottles, even once, they risk exposing themselves to dangerous bacterium, such as fecal coliform and DHEA, transported from their hands and saliva into the water. Additionally, after the first use, the plastic begins to break down, releasing toxic compounds and carcinogens. 

While consumption of bottled water is a luxury rather than a necessity in the United States, the same is not true worldwide. The United Nations found that nearly 1.1 billion people, roughly 20 percent of the world's population, do not have access to safe drinking water. This water crisis is made worse by the fact that only 2.5 percent of the water on Earth is freshwater, compared with 97.5 percent saltwater. Given the rate of freshwater consumption, the United Nations estimates that by 2050, more than two billion people in 48 countries will not have access to freshwater. 

So what can you do to alleviate the impending water crisis? Give tap water another chance. People mistakenly think that because cities such as Detroit and Los Angeles are so polluted, the water must also be dangerous. But just because the water tastes or looks funky doesn't mean it's bad for you. Rather, U.S. tap water is as safe as it gets. 

In the United States, tap water is regulated by the Environmental Protection Agency. This agency monitors the levels of roughly 90 different contaminants, including germs such as giardia, heavy metals such as lead and chemicals such as chlorine. The EPA also requires municipal suppliers to test for contaminants several times a day, state their sources of water and publicize any contaminant found, according to the Los Angeles Times. 

By contrast, bottled water is regulated by the Food and Drug Administration. Unlike the EPA, the FDA requires private bottlers to test for contaminants only once a week, once a year or once every four years, depending on the contaminant. In addition, bottling companies are not required to share any instances of contamination with their consumers nor disclose where the water in the bottle came from. 

Ironically, tap and bottled water come from the same sources: lakes, springs, rivers and aquifers. And contrary to what advertisers would like you to believe, bottled water does come from a tap - you don't really think Evian or Perrier workers are hand-filling individual bottles of water for you? Of course not: pipes run from the source to the bottled water factories, collecting and filling individual bottles from a tap. 

Just because the water is advertised as "glacier fresh" or "natural spring water" doesn't mean it came from a glacier or even anything "natural." In fact, some producers of bottled water, including Dasani and Aquafina, are simply selling filtered tap water to consumers. 

So next time you reach for a bottle of water, think twice about where it came from. Not only will you save yourself some money, but the environment will thank you too.