According to an August 2026 summer hydration report, the Vesper cocktails make the drinker lose the most water in just a few sips. As around a third of US adults show insufficient hydration, especially in hot weather, experts from Instant Hydration reveal trending summer cocktails that deplete the most water from your body the fastest.
- Vesper contains the most alcohol among the trending summer cocktails, at 48.9 mL per drink, which leads to the fastest fluid loss.
- The sweetest drink on the list is Mai Tai, with 22.4 grams of sugar in a single cup.
- Aperol Spritz and Hugo Spritz are the least dehydrating cocktails, both containing under 13 mL of pure alcohol.
The study compared 30+ popular summer cocktails by their effect on dehydration. For each drink, the report calculated the pure alcohol share in a standard recipe and estimated sugar and caffeine. Practical water pairing reflects how much water a person should drink before or after a cocktail to offset the dehydration process.
Here’s how the dehydration effect works in these cocktails and why:
| Cocktail | Serving Size (mL) | Pure Alcohol (mL) | Pre-Dilution ABV (%) | Estimated Sugar (g) | Practical Water Pairing (mL) |
| Vesper | 133.08 | 49.83 | 37.44% | 1.33 | 1000.0 |
| French 75 | 221.80 | 42.14 | 19.00% | 6.42 | 850.0 |
| Margarita | 118.29 | 35.49 | 30.00% | 7.21 | 700.0 |
| Manhattan | 90.56 | 31.87 | 35.19% | 4.61 | 650.0 |
| Spicy Margarita | 100.00 | 32.00 | 32.00% | 7.14 | 650.0 |
| Old-Fashioned | 76.23 | 27.64 | 36.26% | 4.19 | 550.0 |
| Passion-Fruit Margarita | 100.00 | 28.55 | 28.55% | 5.99 | 550.0 |
| Mai Tai | 127.50 | 30.00 | 23.53% | 22.41 | 600.0 |
| Dirty Martini | 73.93 | 24.77 | 33.50% | 0.22 | 500.0 |
| Rosita | 89.64 | 26.29 | 29.33% | 6.88 | 550.0 |
You can find the full cocktail list with a detailed breakdown by following this link.
1. Vesper ❌
- Serving size: 133 mL
- Pure alcohol: 49.8 mL
- Estimated caffeine: none
- Estimated sugar: 1.33 grams
- Practical water pairing: 1,000 mL
The Vesper is the summer cocktail that affects hydration the most, with 1 liter of water needed to replenish what the body loses. This cocktail makes a person lose water so much because of the highest pure alcohol content on the list, with 49.8 mL. As a powerful diuretic, alcohol makes kidneys move water into the bowels, pulling it from the rest of the body.
2. French 75 ❌
French 75 takes second place. While its pre-dilution alcohol concentration is low, at just 19%, it’s actually a stronger cocktail than a Margarita or Long Island Iced Tea. One glass of French 75 contains 42.1 mL of pure alcohol, the second-most on the list, as well as 6.4 grams of sugar. This combination of alcohol and sweetness speeds up the dehydration process, and 850 mL of water is required to offset the loss.
3. Margarita ❌
Margarita is the third-most dehydrating summer cocktail on the list, and it pulls water through its sweetness more than through alcohol. Its alcohol content is still high, at 35.5 mL, and it’s concentrated at 30% before melted ice is added. In a standard 118 mL cup, the drink contains 7.2 grams of sugar, 5.5 times more than in the Vesper.
4. Manhattan ❌
Manhattan also made the ranking of the most dehydrating cocktails. It’s one of the smaller drinks on the list, with a typical serving size of just 90 mL, and a third of it is pure alcohol. The combination of whiskey and vermouth produces one of the highest alcohol concentrations in the study, at 35.2%.
5. Spicy Margarita ❌
Another take on a classic Margarita takes fifth place, with 50 mL of tequila and 30 mL of Cointreau mixed up in just 100 mL of a drink. The pure alcohol content sits at a smaller 32 mL, but the drink still requires 650 mL of water just to stop the body from losing water.
The wellness expert from Instant Hydration commented on the study:
“In summer, it’s especially important to pay attention to what you drink and keep yourself hydrated. Many of these cocktails are go-to during brunches and vacations: they feel refreshing, but the actual effect is the opposite. Add to that sunbathing, physical activity like swimming in the pool, and long nights, and dehydration is a serious risk. It’s not only about feeling thirsty. Dehydration affects your skin in the long run, and it’s even related to chronic illness development.”
This article was written for WHN by Instant Hydration, with 7x the electrolytes of leading sports drinks, their premium formula — powered by naturally superior sel gris — gives your body & mind everything it needs to perform at your peak, instantly.
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