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How Much Water Do We Need to Drink a Day, Eight (8) Glasses?

Updated: Apr 7, 2021

How Much Water Do We Need to Drink a Day, Eight (8) Glasses? James Chin-Ti Lin, MD,

Why Did Water-drinking Issue Come Up?

In 45 years of practicing urology, too many patients complained to me of going to bathroom often, which has inconvenienced and disturbed their life, and asked me to help rid their bothersome frequenting bathroom.

Surprisingly, my asking them why they drink so much water has always incited an instant righteous response by saying: They love and need to drink a lot of water so to flush body-system and they have been taught to drink at least eight (8) glasses of water a day since childhood.

Coincidentally, such notion on water drinking was exactly the same like what I was taught some 60 years ago in schools over other continents like Asia. Does this ubiquitous daily 8-glass water drinking imply the existence of another universal code of daily living?

But, now, they want me to help them. And what and how I can help them as well as what and how they can help themselves has constantly nagged my mind to ponder over what and how I can do to help solve their quest to stop frequenting bathroom. Huey.

Any Medical Precautions? Yes, read on...

Though overconsumption of any fluid like water or any editable drinks may lead to excessive urine production and subsequently urinate often, few medical conditions may further increase urine production for urinary frequency day or night. I list the common medical conditions as follows:

  1. Slow decline in kidney concentrating ability: This, to a degree, may be age-related or chronic-diseases-related like prior kidney inflammation or infection, high blood pressure, prior trauma or surgery-related conditions, etc. As a result, such persons will make more urine than the persons with normal healthy kidneys.

  2. Poorly or uncontrolled high blood sugar in diabetes mellitus can act like water pills to make more urine.

  3. Some one with marginal heart ability: This kind of patients tends to breathe faster than the usual at some stress, so-called exertional dyspnea, and as well, they may start have various degree of water retention in daytime and make more urine at night leading to urinate more often at nighttime. Clinically, these patients may see some puffiness in the lower legs especially around ankles, yet, which may happen to those who have poor circulation in the legs like someone with severe varicose veins.

Note: For those having the above concerns or others not mentioned, always bring your potential concerns to the attentions of your medical professionals.

Eight (8)-Glass Water a Day?

This is quite a pressing demand for help, but against the tide of global pounding with drinking 8 glasses a day.

To overcome such dilemma, my exhausting search for solution from literature and common sense has eventually brought us the following:

“How much water do I need to drink a day?" has been a common question everywhere among daily conversations. As well, “to drink a lot or at least 8 glasses a day in order to flush the system” has been a common and compassionate “wise-person’s” personal and professional advice from friends, relatives, medical professionals and offices, magazines, newspapers, TV or radio talk shows, and even the Internet.

How True Is It for 8 Glasses of Water A Day?

How much truth is it in this notion? And is it medically or personally or just socially correct? And “should I drink a lot of water even though I have to urinate very often, even too often?” To iron out potential confusion in this pressuring issue, I churned up the following two questions to ask and share.

First, are there any mammals on our planet like human beings being taught to drink a lot of water? As I know of or as you probably would agree to, there has been none but human beings - us.

Second, where did we originally learn and discover how we regulate water and electrolytes? Was it directly from human bodies or somewhere else? The truth is from animal laboratory where we used dogs, pigs or monkeys to search and identify the location and function of pressure and chemical sensors for regulating water and electrolytes. Then we extrapolated what were discovered and record them in the textbook of physiology for us to study and learn.

So, we know these well-known sensors are inside our hormonal, circulatory and neurological systems; they provide a delicate “automation” for internal regulation. Thereby, we have a sense of thirst as mammals do and all mammals rely on this natural sense of thirst to decide when and how much they would need to drink for survival and growth. And they do, they do well. Are we human beings really any different from other mammals in this aspect of life?

What Should Be Reasonably Recommended?

Based on such truth and basic understanding, I personally do not advise my patients to drink a lot. Instead, I encourage them to respect and closely listen to their bodies telling them what to do; in other words, they should drink whenever they feel thirsty.

However, I do recommend them to drink more if they have the following conditions:

1. Recurrent urinary stone disease,

2. High-output kidney failure,

3. No or low anti-diuretic hormone (ADH) due to damage to pituitary gland at the

middle low spot of the brain,

4. Poorly controlled diabetes mellitus (high blood sugar),

5. Indwelling catheter from the outside to the urinary bladder or the kidney(s),

6. Gross hematuria (visibly gross bloody urine) from any causes,

7. On special medications with a need to minimize stone formation and kidney/bladder damage, and

8. Excessive sweating under unduly high-temperature environment, hot weather and / or strenuous, vigorous physical activities.

By now, you should have a reasonably clear idea as to how much water you really need to drink a day.

In general, just drink water timely whenever you feel thirsty. If the amount of water you drink is more than what your body needs, you would have no choice to make more urine so you would have to urinate more often.

However, if you insist on following the common “wise-person’s” advice to drink a lot of water, you would have to graciously endure the inconvenience of frequenting bathroom.

As long as you are able to void with steady continual urine flow to empty bladder under a satisfactory control and urine examination (urinalysis) is normal, your bladder should be just fine in its deserved healthy state.

I hope the above discussion can bring you a realistic perspective and insight to answer your concern on “how much water do I need to drink a day?

I wish you well. And have a wonderful healthy life and a happy bladder.


Thank you for reading the post. Before you go, please leave your comment/suggest for improvement as well as helping others; I do appreciate it.

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