You know how important hydration is to your athletic performance and overall health, so we're not going to bombard you with more common knowledge.

But we will share some interesting new facts about hydration you probably don't know. 

Scientists at the universities of Stirling (Scotland), Loughborough (U.K.), and Bangor (U.K.) analyzed the hydration potential of different drinks—not just water and its derivatives, but beverages you wouldn't think to be particularly hydrating.

Currently, there's no beverage hydration index (like there is a glycemic index) to help people understand how to optimize the beverages they drink to stay hydrated. Not all drinks hydrate you the same way, and water isn't necessarily the best.

In the study, researchers tested the effects of 13 commonly consumed drinks* on urine output and fluid balance. Seventy-two participants—who had fasted and abstained from any fluids—consumed either one liter of water or one of the 13 other beverages over the span of 30 minutes. Researchers collected urine for the next four hours to monitor body salt balance, and establish which fluids were retained in the body for the longest period of time. 

“Many people believe that drinking fluids such as tea and coffee causes them to become dehydrated, but we found that when drunk in normal amounts and frequency these drinks do not stimulate any additional fluid loss compared to drinking water,” study author Stuart Galloway of the Health and Exercise Sciences Research Group at the University of Stirling said in a press release

In fact, the researchers discovered several fluids were retained in the body for the same time, or longer, as water. Curious what they might be? Click through our gallery to find out the good, the bad, and the surprising. 

*The researchers didn't include so-called "designer waters" like coconut water, but they can be incredibly useful for staying hydrated during the day as well as post-exercise.