Does Drinking Diet Soda Count Towards Your Water Intake?

January 8, 2026 •

3 min read

According to the CDC, drinking enough water is vital for health, preventing issues like dehydration, constipation, and kidney stones. So, does drinking diet soda count towards your water intake? The answer is yes, but it is far from an ideal fluid source for your body.

Quick Summary

Diet soda, being primarily carbonated water, technically contributes to your total fluid intake. However, due to its additives and acidity, it is not an ideal replacement for plain water for optimal hydration and long-term health.

Key Points

Counts as fluid: As it is mostly water, diet soda technically contributes to your daily fluid intake.
Caffeine's effect is minimal: The mild diuretic effect of caffeine is outweighed by the fluid volume, so it is not dehydrating in moderate amounts.
Not a healthy replacement: Diet soda contains artificial sweeteners and acids that are not beneficial for overall health.
Plain water is superior: Water remains the healthiest and most effective choice for hydration, with no calories or harmful additives.
Consider healthier swaps: Opt for alternatives like sparkling water, infused water, or unsweetened tea for better long-term hydration.

The Simple Answer: Yes, But With a Catch

On the most basic level, drinking diet soda does indeed count toward your water intake. This is because diet soda is overwhelmingly composed of water—some varieties are reported to be up to 99% water. Your body absorbs this fluid, and it contributes to your overall hydration status. For this reason, some health professionals state that all beverages containing water contribute to your daily needs.

The Dehydration Myth and Caffeine Content

There is a long-standing misconception that caffeinated beverages, including diet soda, are dehydrating because caffeine acts as a mild diuretic. However, this has been largely debunked by modern research. The fluid content of the soda is enough to offset the minor diuretic effect of the caffeine, especially when consumed in moderation. A significant amount of caffeine would be required to cause a net fluid loss, which is not the case for the caffeine levels found in most diet sodas. This means you do not need to drink extra water to 're-hydrate' after having a single can of diet soda.

The Health Implications Beyond Hydration

While diet soda can technically hydrate you, it is not a healthy substitute for plain water. The non-water ingredients present in diet soda, including artificial sweeteners, acids, and preservatives, carry potential health concerns that water does not. These additives can have a negative impact on various aspects of your health over time.

Key health concerns associated with diet soda consumption include:

Artificial Sweeteners: These sugar substitutes, such as aspartame and sucralose, can alter your perception of sweetness, potentially increasing cravings for sweet and sugary foods. Observational studies have also linked them to weight gain and an increased risk of metabolic syndrome.
Dental Erosion: Diet soda is highly acidic due to ingredients like phosphoric and citric acid. Regular consumption can erode tooth enamel, increasing the risk of cavities and tooth decay, regardless of the absence of sugar.
Gut Microbiome Disruption: Emerging research suggests that artificial sweeteners may negatively affect the balance of bacteria in your gut, which is crucial for digestion and overall well-being.
Potential for Kidney Issues: Some studies have observed an association between high diet soda intake and an increased risk of kidney problems, potentially due to the high phosphorus content in cola varieties.
Lack of Nutrients: Unlike water, which is a nutrient in itself, diet soda provides no nutritional value. It is essentially flavored, fizzy water with added chemicals.

Water vs. Diet Soda: A Direct Comparison

To highlight the differences, here is a comparison between plain water and diet soda:


Feature	Plain Water	Diet Soda
Hydration Efficiency	Excellent. Best fluid source for the body.	Good, but with potential health trade-offs.
Calories	0	0
Sugar/Sweeteners	0	Artificial sweeteners (e.g., aspartame)
Acidity	Neutral pH. Harmless to teeth.	Highly acidic. Can erode tooth enamel.
Nutritional Value	Essential for bodily functions.	None. Empty calories/additives.
Health Concerns	None.	Linked to potential metabolic, dental, and kidney issues with regular high intake.

Healthier Alternatives to Diet Soda

If you find yourself reaching for diet soda out of habit or for the fizz, there are much healthier alternatives that contribute to your hydration goals without the downsides:

Sparkling Water: This is a great, calorie-free alternative to satisfy the craving for carbonation. It contains no artificial sweeteners or additives.
Infused Water: Add slices of fruit like lemon, lime, or berries, or herbs like mint or cucumber to plain water for a refreshing and natural flavor boost.
Unsweetened Iced Tea: If you're looking for a caffeinated option, brewed iced tea without added sweeteners is a much better choice than diet soda.

Conclusion: The Final Verdict on Diet Soda and Hydration

Ultimately, while drinking diet soda does contribute to your daily fluid intake, it is not the same as drinking water. The presence of artificial sweeteners and acids means it is not the optimal choice for your health. For true, healthy hydration, plain water remains the gold standard, offering all the benefits without any of the potential downsides associated with diet soda. Choosing water over diet soda, especially as a primary beverage, is a simple yet impactful decision for your long-term well-being.

For more information on the benefits of drinking water, consider visiting the CDC's page on healthy drinks.

Frequently Asked Questions

No, you should not replace all of your water intake with diet soda. While it provides fluid, it lacks the purity and health benefits of plain water and contains artificial additives that are not ideal for regular, high-volume consumption.

No, the caffeine in diet soda does not typically cause dehydration. While caffeine has a mild diuretic effect, the fluid content of the soda is greater, resulting in a net hydrating effect when consumed moderately.

Both diet and regular soda are harmful to teeth due to their high acidity. Diet soda lacks sugar, but the acids (like phosphoric and citric acid) can still erode tooth enamel over time, leading to decay.

Better alternatives include plain water, sparkling water, or infused water with fruits and herbs. These options provide hydration without the artificial sweeteners, acids, and other additives found in diet soda.

Some observational studies have found an association between high consumption of diet soda, especially cola, and an increased risk of kidney problems, potentially due to high phosphorus content. However, correlation does not prove causation, and more research is needed.

Yes, some research suggests that the artificial sweeteners found in diet soda can disrupt the balance of your gut microbiome, potentially leading to digestive issues and other health concerns.

While diet soda is calorie-free, observational studies have linked it to weight gain and metabolic syndrome, possibly because artificial sweeteners can increase cravings for sugary foods. Experimental studies, however, have shown mixed results.