Drinking enough water supports energy, focus, digestion, and overall wellbeing. But how much is enough? Some say eight glasses, others say two litres. The truth: your hydration needs depend on your body, activity, and environment.

Here’s a simple calculator to work out how much water you really need- plus expert guidance on when to drink more.

How Much Water Should You Drink Each Day?

The European Food Safety Authority recommends 2.0 litres per day for women and 2.5 litres for men. This total includes both drinks and food.

For a more personalised baseline, use this formula:

35 millilitres of water × your body weight in kilograms

Example:

• 70 kg × 35 ml = 2,450 ml

• About 2.5 litres per day

This formula gives you a baseline. You may need more depending on lifestyle or environment.

How Lifestyle Affects Daily Water Needs

Hydration isn’t static. It shifts with movement, weather, and body changes.

Exercise

Physical activity increases sweat and breathing losses. Add 500 ml to 1 litre on active days.

Hot or Humid Weather

Heat raises fluid loss even at rest. Drink an extra 500 ml or more in warm or humid environments.

High Altitude

Above 2,500m, faster breathing and urination speed up fluid loss. Sip regularly, even when you’re not thirsty.

Illness

Fever, diarrhoea, or vomiting deplete fluids quickly. Water alone may not be enough- electrolytes help replace lost minerals.

Pregnancy and Breastfeeding

The NHS advises that pregnancy increases water needs by around 300 ml per day, while breastfeeding can increase needs by up to 700 ml depending on feeding frequency.

Why Water Alone May Not Be Enough

Plain water is essential but doesn’t always equal full hydration. To absorb and retain it, your body also needs electrolytes like magnesium, sodium, and potassium.

Without them, water can pass through too quickly- leaving you tired, thirsty, or foggy. Electrolytes improve absorption, rebalance fluids, and support energy.

How to Stay Properly Hydrated Every Day

• Use the 35 ml × body weight formula for your baseline

• Sip steadily through the day instead of chugging at once

• Increase intake during heat, exercise, or travel

• Check your urine colour- pale yellow is a good sign

• Add electrolytes for better absorption and balance

• Don’t wait until you’re thirsty- that’s a late signal

POPDAYS Helps You Hydrate Smarter

POPDAYS makes hydration easier by combining water-soluble vitamins and minerals with natural flavour.

• Magnesium to support fluid balance and energy

• Essential vitamins for daily wellness

• Zero sugar, caffeine, or artificial sweeteners

• No plastic bottles

Drop a tablet into your water, let it fizz, and sip through the day. Whether you’re working, training, or travelling, it helps your body absorb and use water more effectively.