How Much Water Should You Drink, and Do You Need Electrolytes?

Most women need about 2.7 litres of water a day, and men about 3.7 litres, counting ALL drinks and food. Thirst and pale-yellow urine are good everyday guides, and for most sessions under an hour, water and normal meals are enough without electrolytes.

That's the answer. Now let's talk about the gallon jug you've been dragging around.

How much water should I drink a day?

Roughly 2 to 3 litres from all drinks and food covers most women. More on hot days or sweaty training days.

About 80% of your water comes from drinks and 20% from food. So the "8 glasses on top of everything else" rule? Made up. Most healthy people meet their needs by letting thirst guide them and drinking with meals. Heat, hard training and long sessions raise what you need.

You're an adult. Your thirst works. Use it.

Do I need electrolytes?

For most sessions under an hour: no. Water and your normal meals do the job.

For long, hot or very sweaty sessions, or race prep: yes, a drink with sodium helps. Drinks with electrolytes and carbs can do more than water alone in those situations.

Here are the daily numbers, so you know what you're working with:

• Sodium: adequate intake is 1,500 mg a day. If you're eating more than 2,300 mg a day, cut back. One gram of table salt holds roughly 388 mg of sodium. Very active people training in heat may need more.
• Potassium: 2,600 mg a day for women, 3,400 mg for men.
• Magnesium: 310 to 320 mg a day for women, 400 to 420 mg for men. The upper limit from supplements and medicines is 350 mg a day, and too much gives you diarrhoea, nausea and cramping. Fun.

Salt is not the devil. Healthy active people need sodium, especially when they sweat a lot. But know your blood pressure. If it's high or borderline, talk to your doctor before adding salt.

Does food cover my electrolytes?

A LOT of it. Processed foods are often loaded with sodium, while veg, legumes, whole grains, nuts and dairy bring the potassium and magnesium. So eating at least 80% minimally processed with veg at every meal does most of the electrolyte work for you. If you want the why behind that, read [What Counts as Ultra-Processed Food](/blog/ultra-processed-food-what-counts).

Should you take magnesium? Food first: legumes, nuts, seeds, whole grains, leafy greens and dairy. Any supplement is a conversation for your doctor or a naturopathic doctor, especially if you take medication or have kidney issues.

How much should I drink around training?

Sweat rate and sweat sodium vary a LOT between people. So a plan built around you beats any one-size rule. Here's how to build it:

• Weigh yourself before and after training. That's your sweat rate. Aim not to lose more than 2% of your body weight in fluid during a session, because that can hurt performance.
• Before: about 5 to 10 mL per kg of body weight, 2 to 4 hours beforehand. For a 70 kg woman, that's about 350 to 700 mL.
• During: a starting point from Andy Galpin (shared on Huberman Lab) is your body weight in pounds divided by 30, in ounces, every 15 minutes, ideally with electrolytes. A 150 lb person drinks about 5 oz (roughly 150 mL) every 15 minutes. Averages, not rules.
• After: about 1.25 to 1.5 litres of fluid with sodium for every kg you lost.

And never race, lift heavy or do intervals fasted. Have carbs and protein 1 to 3 hours before intervals. Timing details are in [How Many Meals a Day Should You Eat to Build Muscle?](/blog/how-many-meals-a-day-protein-timing).

What should I drink for a HYROX race?

A HYROX race is 8 x 1 km runs, each followed by a station: SkiErg, sled push, sled pull, burpee broad jumps, row, farmers carry, sandbag lunges and wall balls. Elite finishers take about 55 to 65 minutes. First-timers often take 90 to 120.

So most of you are out there for over an hour. That means:

• Start hydrated.
• Sip to thirst during the race.
• For sessions longer than about an hour, 30 to 60 g of carbs per hour is a sensible range. Fast carbs like sports drinks, gels, chews and white bread belong right here, around hard and long sessions, where they're fuel.
• Practise your exact race-day drinks and fuel in training. NOTHING new on race day.

More on racing in [HYROX for All Ages](/blog/hyrox-for-all-ages-women-38-60).

Can you drink too much water?

Yes. And this is the one nobody talks about.

Hyponatremia is low blood sodium during or up to 24 hours after exercise. The main cause is drinking more than you lose in sweat and urine. Risk goes up with gaining weight during exercise, events over 4 hours, inexperience, a slow pace, high or low BMI, and easy access to drinks.

In the 2002 Boston Marathon, about 13% of the finishers studied had some degree of it. And it wasn't about being a woman. Body size, race time and drinking habits mattered more.

• Mild signs: light-headedness, dizziness, nausea, puffiness, weight gain.
• Severe signs: vomiting, headache, confusion, seizures, coma. That's a medical emergency.

Prevention is simple: drink when you're thirsty. Sodium drinks soften the drop when intake roughly matches losses, but they can't save you if you keep over-drinking. If you're GAINING weight during a long session, you're over-drinking. Full stop.

Too little shows up as thirst, darker urine and losing more than about 2% of body weight over a session. Headache, dizziness and early fatigue are common too, but they overlap with low fuel and heat, so treat them as a prompt to check, not a diagnosis.

Will drinking more water help hot flashes and night sweats?

It'll help you feel more comfortable. It won't stop them.

Keep water by the bed and top up after a rough night. That's practical comfort, not a treatment. In the 2023 Menopause Society position statement, cooling and avoiding triggers were NOT recommended as treatments because the evidence was lacking. Clinical hypnosis and CBT were. Hypnosis is rated Level I there, alongside the medical options. Hormone therapy is still rated the most effective treatment, and that's your doctor's call. Hypnosis sits next to it, not against it.

Alcohol feeds hot flashes and breaks up sleep. I don't drink, and alcohol-free is our default in perimenopause.

This isn't medical advice. If you have high blood pressure, heart or kidney disease, or take medication that affects fluids or electrolytes (like diuretics or ACE inhibitors), talk to your doctor before changing salt, potassium or fluids. HRT and hot flash medication are your doctor's call. And confusion, severe headache, vomiting, seizures or fainting during or after exercise means medical help now. Chest pain means emergency care.

Quick answers

How much water should a woman drink a day? Roughly 2 to 3 litres from all drinks and food, more on hot or sweaty training days. Thirst and pale-yellow urine are good guides.

Do I need electrolytes for a one-hour workout? Usually not. Water and normal meals are enough. Long, hot or very sweaty sessions are where sodium helps.

Can you drink too much water during exercise? Yes. Drinking well beyond your sweat losses can dangerously dilute your blood sodium. Drink to thirst.

Do electrolyte drinks prevent hyponatremia? Not if you keep over-drinking. They soften the drop, they don't stop it.

I cramp on long sessions. Is it salt? It might be fluid, sodium, fuel or simply fatigue. Weigh before and after, and try a sodium drink on long sweaty sessions.

Sources. National Academies of Sciences (Institute of Medicine). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. 2004. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium. 2019. NIH Office of Dietary Supplements. Magnesium fact sheet. Huberman A. Using Salt to Optimize Mental & Physical Performance. Huberman Lab. 2022. Sawka MN, et al. American College of Sports Medicine position stand: exercise and fluid replacement. Medicine & Science in Sports & Exercise. 2007. Thomas DT, Erdman KA, Burke LM. Joint position statement: nutrition and athletic performance. Medicine & Science in Sports & Exercise. 2016. Hew-Butler T, et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference. British Journal of Sports Medicine. 2015. Almond CSD, et al. Hyponatremia among runners in the Boston Marathon. New England Journal of Medicine. 2005. The North American Menopause Society. The 2023 nonhormone therapy position statement. Menopause. 2023. prommer.net. What Is HYROX? The Fitness Race Explained. 2026.