How much water is needed and why adding salt is important
Question to Ai – regarding water intake & Hydration dynamics in a person ;
We’re often asked how much water a person should drink. For years, we’ve shared a hydration protocol with our customers, but as our understanding of proper hydration continues to evolve, we realized it was time to explore this important question more deeply. So, we turned to AI for additional insight—and here’s the answers we received.
Our Questions:
- For a person weighing 85kg, and being healthy, and drinking 2.5l of water per day, what would be approx his daily liquid output from Breath, urine, sweat, stools etc
- Secondly, from his output, how much water should he drink not to create an imbalance and dehydrate. Also, the output contains minerals that need to be replaced with sea salt, how much salt should he have not to create deficiencies ?
AI DEEPSEEK response:
This is a great physiological question. Let’s break it down step by step, using standard clinical averages for a healthy 85 kg adult male (as males typically have higher metabolic rates and fluid turnover than females) in a thermoneutral environment (not sweating heavily from exercise or heat).
1. Approximate Daily Liquid Output
Total Typical Daily Output = 2,150–3,350 L – In a steady state, output matches input (2.5 L)
Notes for Typical Volume (mL/day) of Daily Losses :
Sensible Losses:
- Urine Loss = 1,200–1,800 ml
- ( varies most with intake; at 2.5 L intake, urine output will be on the higher end (~1,500–1,800 ml)
- Stools 100–200ml Normal; >200 ml suggests diarrhoea
- Sweat 100–500ml. At rest in cool environment; can be 1–2 L/hour with heavy exercise, but here minimal.
Insensible Losses :
- Breath 350–450ml Water vapor from lungs; increases with exercise, dry air, high altitude.
- Skin (diffusion) 300–400ml Not visible sweat; constant loss through skin
For a healthy, sedentary 85 kg person drinking 2.5 L/day in mild climate: Water Losses =
- Urine: ~1,600 ml
- Breath: ~350 ml
- Skin diffusion: ~350 ml
- Sweat: ~200 ml
- Stools: ~150 ml
- Total output/ Losses : ~2,650 ml
That slightly exceeds 2.5 L intake, but the difference is covered by metabolic water (about 200–300 mL/day from oxidation of food) and water content of solid food (~700–1,000 mL/day), which you didn’t count but exist in total water balance.
A practical rule: thirst and urine colour (very pale yellow) are better guides to dehydration than a fixed volume of water to consume.
2. How Much Water Should He Drink to Avoid Dehydration?
If we look only at liquid water intake (ignoring food water and metabolic water), and assume his total water loss is ~2,650 mL from the above routes, then to maintain zero net water balance, his total water input (liquid + food + metabolic) must equal ~2,650 ml.
If he drinks 2.5 L of water, and since food provides ~600 ml and metabolism provides ~250 ml, his total water intake is approximately 3350 ml per day.
That means 1.6 L ( 2650 ml – 850 ml ) of plain water (not other beverages) is sufficient to prevent dehydration in a resting, healthy 85 kg male in a temperate climate **
The 2.5 L/day he is currently drinking is above the minimum requirement, leaving a generous safety margin. If he is active or in heat, losses rise and intake must increase accordingly.
** NB – If he is sick and needs to detox (and the only way of proper detox is with generous water and salt intake over 7-12 months), then the water and salt intake must rise 3-4 L per day and sea salt intake must rise to 7.5 to 11 g (from 6-9 g) – daily.
3. Mineral Losses and Sea Salt Replacement
Water output contains electrolytes, primarily sodium and potassium, with smaller amounts of magnesium, calcium, and chloride.
Daily Sodium Losses (approximate)
Route of Sodium Loss (mg sodium)
- Urine 2,300–3,000 mg sodium
- Sweat 200–500 mg sodium (resting)
- Feces 20–50 mg sodium
- Total 2,500–3,500 mg sodium/day
and thus Equivalent replacement via Sea Salt
- 5.8–7.5 g salt – replacing loss through urine
- 0.5–1.3 g salt – replacing loss through sweat
- 0.05–0.13 g salt – to replace loss through feces
- 6–9 g salt/day – increase if water intake increases for detox
Summary
Question Answer
- Daily output (breath, urine, sweat, stool) ~2,600–2,800 mL for an 85 kg healthy male at rest with 2.5 L intake.
- Minimum liquid water to avoid dehydration ~1.6 L/day (assuming food and metabolic water contribute ~1 L total) – this has to be increased to support detox !
- Sea salt to replace output minerals (if no dietary salt) ~6–9 g/day (this = 2.5–3.5 g sodium)
Caveat : Supplementary potassium and magnesium also needed; sea salt alone is insufficient for full electrolyte replacement.
If this person is drinking 2.5 L of water daily and eating a normal diet, they are likely in excellent water and electrolyte balance. If they are drinking only plain water, then adding 6-9 g sea salt + potassium + magnesium supplementation would be prudent – speak to a healthcare provider for Potassium and Magnesium supplementation.