How Much Water Do You Really Need? Hydration and Wellness

Dehydration of just 1–2% of body weight:

• Reduces cognitive performance by up to 20% — for more on protecting focus, see our focus and distraction guide
• Increases perceived effort during exercise
• Disrupts mood (increases tension, anxiety, and fatigue)
• Slows metabolism
• Reduces kidney filtration efficiency

Chronic mild dehydration is associated with kidney stones, urinary tract infections, and constipation.

A practical formula:

Base intake: 35ml per kg of body weight

• 60 kg person: approximately 2.1 litres daily
• 80 kg person: approximately 2.8 litres daily

Add for:

• Exercise: 500–750ml per hour of moderate exercise
• Hot climate: 500ml–1 litre extra on hot days
• High caffeine intake: add approximately 200ml per large coffee

Urine colour:

• Pale yellow (straw-coloured): Well hydrated
• Dark yellow: Mildly dehydrated — drink water now
• Amber or brown: Significantly dehydrated — drink immediately
• Colourless: Possibly over-hydrated — reduce intake slightly

Other dehydration signals: afternoon headache, difficulty concentrating, dry mouth, constipation.

Structure water intake so it becomes automatic:

• On waking: 500ml before coffee or breakfast
• Mid-morning: 500ml during the first half of your workday
• With lunch: 250–500ml
• Mid-afternoon: 500ml (addresses the 3pm energy slump)
• With dinner: 250ml

Total: approximately 2–2.5 litres from drinks alone.

Add electrolytes when:

• Exercise lasting more than 60 minutes — whether that is a daily 10,000-step walk or a HIIT session
• Heavy sweating in heat
• Illness with diarrhoea or vomiting
• Low-carb or fasting protocols

Natural sources: pinch of sea salt in water, coconut water, banana + water.

Over-hydrating with plain water without electrolytes during prolonged exercise can cause dangerously low sodium — rare but serious.