Ohh bottled water... The convenience of having a product -- that you can get for free -- bottled for you has turned into a more than $18 billion industry in the U.S.

So if you're going to pay for it, you might as well know where it's coming from.

Half of all bottled water is just tap water

PepsiCo, the maker of Aquafina, will soon be changing its label in order to make it clear to consumers where the bottled water is coming from. The new labels will include "public water source," to clarify that the water is really just tap water. Before going into an Aquafina bottle, the water is purified through a seven-step process, removing minerals and other contents that may be found in municipal water supplies.

“If this helps clarify the fact that the water originates from public sources, then it's a reasonable thing to do,” PepsiCo spokeswoman Michelle Naughton told ABC news.

Read more: Why you should stop drinking bottled water

Why bottled tap water is a ripoff

According to the Beverage Marketing Association, a trade group, nearly 50% of all bottled water sold in the U.S. is just tap water that's been purified. The regulated standards for bottled water and tap water are actually very similar. The biggest difference is that bottled water is produced specifically for "human consumption."

But with that said, tap water is regulated by the Environmental Protection Agency (EPA) to ensure that it's safe to drink, and many experts say tap water is actually regulated more tightly than bottled water. There's just no fancy label on your faucet. Plus, tap water typically contains fluoride,  which helps maintain strong teeth and prevent tooth decay, and fluoride is often removed from bottled water during the purification process. 

In fact, an Australian study cited by The Washington Post found that kids who don't drink fluoridated tap water have a more than 50% higher incidence of cavities.

You should be able to get information about your local drinking water on your local government's website. If you have any concerns, the EPA has a guide on how to test your own water.

Read more: Study: Dollar General & Walmart have the cheapest prices

Non-tap bottled water 

Bottled water that doesn't come from a municipal source is labeled differently, but bottlers have made it difficult for consumers to tell the difference. For example, "mountain water" and "glacier water" are not FDA standard phrases -- so if you see either of those on a label, they really mean nothing.

If you're looking for water that comes from a "pristine" source, which means the source is protected and therefor the water is less likely to contain any contents that could be harmful to people with weakened immune systems or other health issues, look for these identifiers:

  • Artesian water
  • Spring water
  • Well water 

According to the FDA, these labels indicate the water is from "an underground aquifer which may or may not be treated. Well water and artesian water are tapped through a well. Spring water is collected as it flows to the surface or via a borehole." The water then must meet the FDA's bottled water standards.

How to save

According to Consumer Reports, someone who buys a $1 bottle of water every day will end up spending 700 times the amount they would spend on drinking tap water -- in one year. Plus, according to the environmentalist group Food & Water Watch, water bottles account for 1.5 million tons of plastic waste per year, and require 47 million gallons of oil to produce. So if you're looking for a way to save, tap water is the way to go.

But if you have to have bottled, or purified, water, you might as well save on it.

Filter the water yourself

Whether it's for taste or health concerns, you can save a lot of money by filtering your own water at home (rather than buying bottled water). The prices of filters vary -- from less than $20 to hundreds of dollars, depending on your needs and the amount of water you want to filter. Check out Consumer Reports' guide to buying water filters here.

Buy cheap bottled water

If you don't want to fool with filtering your own water -- and you prefer the taste and convenience of bottled water -- look for cheaper options. When you buy it in a case, you can pay about 8 cents per bottle at places like Costco and Aldi. At Sam's Club it costs about 10 cents a bottle. Even at traditional supermarkets, you can typically get bottled water for around 15 cents a bottle (when you buy a case).