Sparkling water: is it as healthy as tap water?

What is sparkling water?

Sparkling water is water with carbon dioxide dissolved in it—the gas that makes the bubbles. When it dissolves, it forms carbonic acid, which gives the water its slightly acidic, sharp taste.

If it is natural mineral water, the label states where the gas comes from [1]. “Naturally carbonated” means the gas comes from the spring itself. “Fortified with gas from the same spring” means more gas from that source has been added. “With added carbon dioxide” means the gas comes from elsewhere [1]. Soda water or siphon water is drinking water with added gas; it does not have the mineral composition of spring water.

Water provides no energy, carbohydrates, fat or protein. That is why its label does not include the nutrition table found on other foods: water is exempt [2]. Instead, natural mineral water lists its analytical composition [1]. This includes sodium, calcium, magnesium and bicarbonate, in milligrams per litre, and the amounts vary greatly from one spring to another.

Does sparkling water hydrate as well as still water?

Yes, it hydrates just as well. A trial comparing several commonly consumed drinks found that the body retains the same amount of fluid from sparkling water as from still water [3].

So it counts towards your hydration just like any other water. The European reference for total water intake is around 2 litres a day for adult women and 2.5 litres for men, including water from food [4]. If you find plain water hard to drink and the bubbles encourage you, it can be an easy way to get closer to that amount.

Your needs change with intense exercise or hot weather. They can also change for older people and during pregnancy or breastfeeding. For advice on what to drink during intense exercise or hot weather, see our guide to sports drinks.

Does sparkling water cause weight gain or bloating?

It does not cause weight gain, because it contains no calories. How it feels for you depends on the individual. The gas you drink has to come out, and for some people this means burping or bloating in the upper abdomen. This is temporary discomfort that goes away when the gas is released.

Reflux needs a little more nuance. The US reflux guideline includes carbonated drinks among foods that may worsen symptoms, while acknowledging that the evidence is limited [5]. The practical approach is to notice whether it gives you heartburn. If it does, reduce the amount and see whether you feel better.

Does sparkling water harm your teeth or bones?

Carbonic acid makes sparkling water slightly more acidic than still water. The risk to tooth enamel depends on how acidic a drink is and how many times a day you have it.

Carbonated soft drinks are usually below the pH at which enamel starts to dissolve, and having them often encourages erosion [6]. Plain sparkling water does not contain their added acids or sugar, and its risk is much lower. If you squeeze in lemon, the risk of erosion increases a little because lemon is acidic too.

For bones, the concern comes from soft drinks. An analysis of 26 studies linked high consumption of sugary drinks with lower bone density in adults [7]. We have no evidence pointing to the same effect from unsweetened sparkling water.

How is it different from a soft drink or flavoured water?

The main difference is sugar. A soft drink contains water, carbonation and, almost always, added sugar, acids and flavourings. That sugar is free sugar. The WHO recommends that it provide less than 10% of daily energy intake and, ideally, less than 5% [8]. On a diet of around 2,000 kcal, that is about 50 g a day [8]. A can of sugary soft drink uses up a large part of that allowance.

Sugar-free versions do not add free sugar, although they are still acidic drinks [6].

Flavoured waters fall somewhere in between. Some are water with carbonation and flavourings, and nothing else. Others contain sugar or concentrated juices, making them more like soft drinks. The first line of the ingredients list will tell you.

How to choose sparkling water by reading the label

The figure that matters most is sodium per litre, in the analytical composition. It varies greatly from one spring to another, and European regulations set two reference points [1]. If the label says “suitable for low-sodium diets”, it contains less than 20 mg per litre. If it says it contains sodium, it has more than 200 mg per litre [1].

For context, the recommendation for adults is to have less than 5 g of salt a day (about 2 g of sodium) [9]. One litre of water containing 200 mg of sodium already provides at least a tenth of that limit. With water containing less than 20 mg per litre, the sodium from the water hardly counts towards your intake.

If you have high blood pressure or kidney disease, or you have been asked to watch your salt intake, choose water with less sodium. Discuss it with your doctor or dietitian-nutritionist.

What we hear in consultations about sparkling water

In consultations, sparkling water usually comes up for three reasons.

“I only drink water if it’s sparkling.” For many people, it is a way to drink throughout the day without getting bored, and we are happy with that. We just suggest checking the sodium if you drink more than a litre a day.

“I fill up on sparkling water so I don’t snack.” The bubbles can make your stomach feel full for a while, and some people use them to calm their hunger. If this sounds familiar, it is worth talking about it calmly. If you are also concerned about your relationship with food, find out how we work in our dietitian support for eating disorders.

“Sparkling water is good for digestion.” Some people find it sits well after a meal, and there is no problem with drinking it. We do not have solid evidence that it improves digestion, so we do not recommend it as a remedy.