If you’ve ever cracked open a can of seltzer, you know that sparkling water is far more carbonated than still. Sparkling water is famous for its bubbly surface, sharp texture, and hissing sound in comparison to plain water from a tap or bottle. 

We know that water is great for us–it’s recommended to drink 8 cups of water a day–but what about sparkling water? How does its carbonation affect its ability to leave us healthily hydrated? In this post, we’ll explore the differences between the two types of water and whether one is more hydrating. 

What are the Major Differences between Sparkling and Still Water? 

Sparkling water is made from two main ingredients: carbon dioxide and–you guessed it–water. 

Many brands of sparkling water contain mineral additives, including potassium and sodium bicarbonate.

There are several major types of carbonated water.

1. Mineral water. This type of fortified water includes natural gas and nutrients. In some brands, the level of carbonation is enhanced through additional carbon dioxide. 
2. Soda water. Carbonated water that contains the compound sodium bicarbonate is known as soda water. 
3. Tonic water. Water that has been enhanced with carbon dioxide, minerals, and quinine–a bitter-tasting compound–is known as tonic water. Some tonic water brands also include sweeteners. 
4. Sparkling water. This is the general term for water that has been carbonated through the artificial addition of carbon dioxide. 

Which is More Hydrating? 

Studies have shown that there is little to no difference in the hydrating effects of sparkling water versus still water. 

That’s because carbonation by itself doesn’t have an effect on the way the body processes water. While the increased volume of carbonated water may cause the beverage to be processed by the stomach more quickly, the ultimate difference in hydration when compared to regular water is negligible.

The BHI–a scientific term for “beverage hydration index”–was the same for sparkling and still water in a study that investigated the effects of 13 different types of drinks on the body’s hydration levels.

The catch? Sparkling water with added flavors may make one feel more satiated than plain water–even though the levels of hydration are the same. Over the course of a day, this might lead one to drink less water than they would have if they were sticking with plain.

How To Choose What’s Better for You

If sparkling and still water both have similar levels of hydration, which one should you drink? 

The answer comes down to personal preference–as well as which drink encourages you to consume more overall water throughout the day. If you prefer the crisp taste of sparkling water to still, then sparkling water may be better because it motivates you to drink more overall. 

But if the taste of sparkling water prevents you from feeling thirsty for long stretches, it’s possible that you’re not compensating by drinking enough plain water–and therefore aren’t hydrating enough. 

For some, a balanced blend between plain, tap water and the occasional glass or can of seltzer may be the optimal solution to ensure complete hydration and health.