By Jacqueline Howard, CNN
The science is clear: Staying hydrated and drinking enough water has health benefits.
Hydration can help lubricate and cushion joints, protect sensitive tissues in your body, flush out waste and keep your immune system and even your skin healthy.
Yet when it comes to bottled water, there are several types on the market: spring, purified, mineral, artesian and even alkaline. Is any type best?
It turns out that might come down to personal preference, as more research seems to be needed for a definitive answer.
"For the price, I'm going to get spring water," said Dr. Eddie Fatakhov, a physician and nutritionistat the Center for Internal and Integrative Medicine in Alpharetta, Georgia. "Because I know it came from the spring."
Spring, purified, mineral, artesian: What's the difference?
Spring water comes from an underground source and must be collected at the spring or through a borehole tapping the spring's source, according to the International Bottled Water Association.
The association defines purified water as water that has been highly treated -- through distillation, deionization or other suitable processes -- in order to meet certain standards before being sold.
Mineral water is natural water that has a constant level and relative proportions of mineral and trace elements -- containing no less than 250 parts per million total of dissolved solids, according to the water association. No minerals can be added to it.
Then there's artesian water, which is derived from a well that taps a specific layer of rock or sand.
You also might have seen alkaline water on store shelves; it has a higher pH level than tap water. A pH level is a measure of how acidic or basic water is. Seven is a neutral pH. Higher pH levels are more alkaline, or basic; lower pH levels are more acidic.
"Tap water has a pH of roughly around 7, and alkaline water is closer to about 8 or 9," Malina Malkani, a registered dietician nutritionist and spokeswoman for the Academy of Nutrition and Dietetics, told CNN in January.
Could alkaline water provide any special health benefits? "There's really not a lot of evidence either supporting of the health claims that are made about alkaline water or refuting the claims," Malkani said.
In other words, the jury is still out.
Malkani noted that "if all the body systems are functioning as they should be, the blood pH isn't going to vary too much. So it's a misconception that you can, by drinking an alkaline water, drastically affect the pH of the body."
Illnesses are common causes for changes in the blood pH level. Diabetes can make your blood more acidic, but kidney problems can make it more alkaline. Certain foods, including dairy products, also can make your blood more acidic.
It is more common for companies to manufacture alkaline water, but natural alkaline water can occur when water picks up minerals from areas such as springs, when it passes over rocks in the environment.
"Alkaline compounds are salts and metals that, when added to water, make it more basic," Malkani said.
All in all, the general consensus among health experts for now is that making sure you are drinking enough water is more important than the type of water you prefer.
The National Academies of Sciences, Engineering, and Medicine recommend that men drink an average of about 3.7 liters (125 ounces) of water each day and that women drink about 2.7 liters (91 ounces). That water can come from beverages and foods, according to the recommendations.
So, for men and women respectively, "that's 15 cups of water and 11 cups of water, from the eight cups we were taught to believe," Fatakhov said.
Women who are pregnant or breastfeeding need additional fluids to stay hydrated, according to the Mayo Clinic, which noted that the Office on Women's Health recommends that women who breastfeed consume about 13 cups of fluids a day.
"America is dehydrated," Fatakhov said, and that's a problem because "83% of your lungs is water. If you take the heart and the brain, 73% is water. If you take the bones, about 31% is water. If you take the kidneys and muscles, about 76% is water. Your body is made up of water."
'Water boosts energy'
Water not only benefits your health, it could help you control your weight.
A study published in the Annals of Family Medicine in 2016 found a significant association between not being adequately hydrated and having an elevated body mass index, known as BMI.
BMI is determined based on a person's height and weight. Having a BMI of 30 or higher is categorized as obese.
The study was based on data from 9,528 people ages 18 to 64, whose levels of hydration were measured in urine samples. Those whose samples showed inadequate hydration tended to have higher BMIs and higher odds of being obese, compared with the hydrated adults.
"Because of our high water content, it makes sense that our bodies need water to keep our systems functioning. So the next time you hit that afternoon slump, drink a glass of water to increase your energy levels," Fatakhov said.
"Think about it like this: I tell you to drink water, and you drink water. Your body has to convert that water back to your body temperature. So if you drink cold water, your body has to turn it back to body temperature," he said. "That's why they say it's better to drink cold water than hot water if you're trying to burn calories."
If you think you're not drinking enough water, the US Centers for Disease Control and Prevention offers some tips:
Carry a water bottle with you throughout the day for easy access to water.
Choose water instead of sugar-sweetened beverages, even when eating out.
Add a wedge of lime or lemon to water to help improve taste.
Try chilling freezer-safe water bottles for easy access to ice-cold water throughout the day.