How Much Water Should You Drink When You're Drinking Alcohol? The Actual Answer

"Drink water" is the universal hangover advice. It's also almost completely useless as stated, because it doesn't tell you how much, when, in what form, or why — which means most people do it wrong even when they're trying.

They drink a glass of water before bed when they're already significantly dehydrated. They skip the water entirely because they were having fun and forgot. Or they drink so much water at the end of the night that they're running to the bathroom at 3am while simultaneously not absorbing the fluids efficiently because they have no electrolytes in their system.

This guide is the actual answer to the hydration question: not "drink water" but how much, when, why, and what form works best. It's based on current sports science and alcohol metabolism research, and it's actionable in a way that generic advice isn't.

The Basic Biology: Why Alcohol Dehydrates You

Alcohol is a diuretic, which means it increases urine output beyond what you'd expect from the liquid you consumed. The mechanism is well-understood: ethanol suppresses antidiuretic hormone (ADH), also called vasopressin, which is the hormone that signals your kidneys to retain water. With ADH suppressed, your kidneys produce significantly more urine than normal — even if you're sipping steadily, you're losing fluid faster than you're taking it in.

Research published in the British Journal of Nutrition found that alcohol causes approximately 100–150mL of excess urine output per standard drink. Over a night of four drinks, that's 400–600mL of additional fluid loss beyond what you'd normally produce. Combined with any sweating (from dancing, warm environments, or elevated heart rate), you can end up genuinely dehydrated by the end of an evening even if you felt fine throughout.

The dehydration problem is compounded by electrolyte loss. Your kidneys don't just excrete water — they excrete the electrolytes dissolved in that water: sodium, potassium, and magnesium. These minerals are essential for cell function, nerve signaling, and the biochemical processes that keep you feeling like a human being. Magnesium deficiency specifically is associated with headaches and the "fog" of a hangover morning. Sodium loss contributes to the impaired ability to retain water even when you're drinking it.

This is why plain water, consumed in large quantities after drinking, is less effective than you'd expect. Without electrolytes to help your cells actually absorb and retain fluid, a significant portion of the water you drink passes straight through. This is not a fringe theory — it's the same principle behind oral rehydration therapy (ORT) used in clinical settings, which consistently outperforms plain water for treating dehydration.

How Much Water Do You Actually Need?

Here's the specific, research-informed guidance:

Before You Start Drinking

Most people arrive at a party or bar already mildly dehydrated from their day. Office environments with dry air, coffee consumption, and general busyness mean that by 7pm, you're probably not fully hydrated before you've had a drop of alcohol. Starting a night of drinking in a mild dehydration deficit makes everything worse.

What to do: Drink 16–20oz (two full glasses) of water in the hour before you start drinking. This isn't about compensating for what's coming — it's about starting from a neutral baseline rather than a deficit. Also eat a meal containing fat and protein, which slows the absorption of alcohol and reduces peak blood alcohol concentration.

During Drinking

The highest-leverage intervention point is during drinking, not before or after. The advice to alternate water and alcohol is scientifically sound, and here's the math that makes it concrete:

One standard drink causes approximately 120mL of excess urine output (using the midpoint of the research range). A glass of water is typically 240mL. So alternating one drink with one glass of water doesn't fully compensate for the fluid loss from the alcohol — it's about 50% replacement. But 50% replacement is dramatically better than 0%, and it's enough to meaningfully change how you feel the next morning.

What to do: Drink one 8oz glass of water for every drink you consume. This is achievable, doesn't require willpower in the usual sense (it becomes habit after a few times), and makes a measurable difference. If you can get that water to contain electrolytes — by using a mixer like OFTN that includes sodium, potassium, and magnesium in the drink itself — you improve the effectiveness significantly.

The electrolyte piece matters because of the osmotic gradient principle: cells absorb water more efficiently when there are electrolytes present to create the osmotic pressure that pulls water across cell membranes. Electrolyte-enhanced water is absorbed faster and retained longer than plain water. This is the same reason athletes use sports drinks rather than plain water during extended activity.

Electrolytes While Drinking: The OFTN Approach

The most elegant solution to the during-drinking hydration problem is to build electrolytes into the drinks themselves. This is what OFTN was designed to do. Every sachet of our Watermelon Margarita, Yuzu Ginger Mule, and Pineapple Mimosa mix contains sodium, potassium, and magnesium alongside B vitamins — so that every cocktail or mocktail you make is also partially replenishing what you're losing.

This doesn't eliminate the need for additional water. But it meaningfully raises the floor of your hydration status throughout the evening, which changes the math significantly by the time you go to bed. Read more about this in our full hydrating cocktails guide.

Before Bed

This is where most people finally reach for water, and it's better than nothing but far from optimal given that most of the dehydration has already occurred. That said, before-bed hydration does meaningfully reduce next-morning symptoms.

What to do: Drink 16–24oz of fluid with electrolytes before sleep. Plain water is fine; water with electrolytes is better (a sports drink, a coconut water, an electrolyte packet, or an OFTN mocktail build). The goal is to give your kidneys something to work with overnight rather than scraping the barrel for fluid.

There is such a thing as drinking too much water before bed: consuming very large amounts of plain water (32oz+) late at night can cause your body to excrete more sodium as it tries to maintain osmotic balance, potentially worsening the electrolyte situation. Moderation applies here — 16–24oz is the sweet spot, and including electrolytes prevents the overcorrection problem.

The Morning After

Morning hydration should be the first thing before coffee, before food, before checking your phone. Your body has been running a fluid deficit for hours at this point.

What to do: Drink 20–32oz of electrolyte water first thing. Then eat before coffee — food stabilizes blood sugar, which is typically low from overnight alcohol-induced hypoglycemia. Coffee can come third. The order matters: caffeine on an empty, dehydrated system significantly increases the irritability and headache component of a hangover.

The Complete Hydration Timeline

Putting it all together in a single, actionable framework:

What About Coconut Water?

Coconut water has been marketed heavily as a hangover cure, and there's some basis for the hype. Coconut water is naturally high in potassium — one cup contains approximately 600mg, more than a banana — and also contains sodium, magnesium, and phosphorus. This electrolyte profile makes it genuinely good for rehydration, comparable to commercial sports drinks but with natural ingredients and without artificial colors or flavors.

The caveat: coconut water also contains natural sugars (around 6g per cup), so it's not zero-sugar. And the sodium content is lower than drinks specifically formulated for rehydration, which means it's a solid option but not superior to a purpose-formulated electrolyte product for severe dehydration states. For mild to moderate dehydration — which is what most drinking nights produce — coconut water is excellent.

Why Plain Water "Doesn't Work" (and When It Does)

Plain water is perfectly good for everyday hydration and for mild fluid replacement. The reason it underperforms after drinking is the osmotic issue mentioned above: without electrolytes, your cells are less efficient at absorbing and retaining water. In a drinking context, this is the gap that matters.

If electrolyte-enhanced water isn't available to you (you're at a bar, you're traveling, you forgot), plain water is still dramatically better than nothing. The fundamental goal is replacing lost fluid volume, and plain water does accomplish that — just at a lower efficiency rate. Don't let perfect be the enemy of good here: drink whatever water is available.

The Bottom Line on Hydration and Alcohol

The research is clear and consistent: electrolyte-enhanced hydration, distributed across the entire evening rather than concentrated at the end, produces the best outcomes for feeling good the next day. This isn't a wellness trend claim — it's the same principle used in clinical oral rehydration therapy and athletic recovery science, applied to a social drinking context.

OFTN was built around this principle. Our mixes include electrolytes in every sachet because we believe your cocktail should be doing something useful for your body, not just delivering flavor. The hydrating cocktails guide has specific recipes that apply this principle. The hangover science article covers the broader biology. And the low sugar cocktail guide shows how to combine better hydration with better flavor choices across the whole evening.

The short version: start hydrated, stay hydrated throughout, use electrolytes not just water, and go to bed with something in your system. Everything else is optimization at the margins.

Try OFTN — the cocktail mix that hydrates while you celebrate.