Affiliate & partner disclosure: This article contains affiliate links, and I may earn a commission if you buy through them at no extra cost to you. As an authorised LifeWave Brand Partner, I have a financial interest in promoting LifeWave products. Testimonial/editorial given by a LifeWave brand partner with financial interest in promoting the product. Full disclosure at the end.
A note before we start. If you have heart, kidney or liver disease, or your doctor has told you to limit fluids, follow their advice rather than general guidance. This article is general information, not medical advice. LifeWave X39 is a non-transdermal, general-wellness phototherapy patch that gently stimulates the skin with light to support the body’s natural energy flow for strength and stamina. It is not a treatment for any condition.
“Eight glasses a day” is one of the most repeated bits of health advice, and one of the least precise. How much you need depends on your size, activity, climate and diet.
Key takeaways
- Needs vary; a rough starting point is 30–35ml per kg of body weight a day, including food.
- Food provides roughly a fifth of your water.
- Tea and coffee count.
- Pale-straw urine is a good everyday guide.
- Drinking huge volumes quickly can be dangerous.
Where “8 glasses” came from
It’s often traced to a 1945 US recommendation of about 2.5 litres a day — which also noted that most of it comes from food. That caveat got lost.
How much do you need?
A rough estimate is 30–35ml per kg per day of total water. For an 80kg man that’s about 2.4–2.8 litres, including water from food. Drink more for exercise, heat, altitude, illness and high-protein diets.
Does food count?
Yes. Cucumber, lettuce, tomatoes and many fruits are 80–95% water. Tea, coffee and milk count too.
Signs you’re not drinking enough
- Dark yellow urine.
- Tiredness, headaches, poor concentration.
- Dry mouth and lips.
- Worse training performance.
Can you drink too much?
Yes. Drinking very large amounts of plain water quickly can dilute blood sodium (hyponatraemia), which can be dangerous. It’s mostly a risk in long endurance events. Electrolytes matter when you sweat heavily; I use Perform electrolytes, especially around sauna and training.
Get the Simply Younger daily email
One short email a day: the newest post, what I’m testing, and what’s actually working for men over 40.
Join free →Where does X39 fit? Not here. Hydration is about fluids and electrolytes. I wear an X39 daily as a separate general-wellness habit.
Frequently asked questions
Do coffee and tea count?
Yes. Their net effect on hydration is positive for regular drinkers.
What colour should urine be?
Pale straw. Dark yellow suggests you need more; completely clear all day may mean more than you need.
Why do electrolytes matter?
Sodium, potassium and magnesium help maintain fluid balance, especially when you sweat a lot.
Does X39 treat any condition?
No. No such claim is made. X39 is not intended to diagnose, treat, cure or prevent any disease.
Related reading
What Are Electrolytes? · Why Am I Always Tired? · Sleep and Longevity
Full disclosure. This article is general information, not medical advice. LifeWave X39 is not intended to diagnose, treat, cure or prevent any disease; statements about it have not been evaluated by the FDA. As an authorised LifeWave Brand Partner I have a financial interest in promoting LifeWave products.
Leave a Reply