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Can drinking more water relieve constipation?

How effective is water therapy for constipation?

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First published: 11.Oct.2018

Constipation is a condition in which a person has slow intestinal transit with an output of small and hard stools with infrequent (fewer than three bowel movements per week) and difficult, or even painful passage.

It afflicts millions of people around the world (perhaps 20% of the world's population suffers from constipation) and can occur in any age group.

The most common recommendation given to constipated patients is to increase fluid intake to improve bowel movements.

In this article, we will review the scientific facts behind constipation and learn if water can help treat or relieve it.

Hydration may help treat constipation.

What causes constipation?

There are many possible causes for constipation:

  • A diet low in fiber (lacking fruit, vegetables, grain, roughage).
  • Not drinking enough fluids.
  • Sedentary lifestyle (lack of exercise).
  • Changes in diet or daily routine.
  • Side effects of medication.
  • Mood changes: depression, stress, anxiety.
  • Not listening to your body: ignoring the urge to go to the toilet.
  • Medical conditions (some of these can be quite serious).

Some of the following medical conditions may cause constipation: bowel obstruction, abdominal cancer, neurological problems (multiple sclerosis, Parkinson's disease, stroke), diabetes, hormonal problems (thyroid or parathyroid glands).

How food is digested

Food is digested in a semi-continuous process that begins when it is chewed and mixed with saliva in the mouth. After being swallowed it reaches the stomach through a tube called the esophagus.

In the stomach, it is broken down by some enzymes and hydrochloric acid, and released into the small intestine with additional gastric juices from the gall bladder and pancreas.

The walls of the small intestine absorb the nutrients contained by the now broken-down food and send them into the bloodstream on its way to further processing, use, and storage.

The small intestine can absorb up to 4 gallons of fluids per day (15 liters).

What remains moves into the large intestine where trillions of microbes contribute to the final stages of digestion. Most of the water that remains in what is now "waste" is absorbed.

The final segment of the large intestine, the colon, absorbs the remaining water (up to 1.3 gallons per day - 5 liters), returning these fluids to the body.

The resulting waste, which is a mix of undigested fiber and millions of bacteria is stored in the rectum and finally expelled as stool from the body regularly.


Constipation is a condition that affects this final part of the digestive process: passing stools.

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The link between water and constipation

The reasoning behind suggesting that a higher water intake can cure constipation is that it will balance the fluids extracted by the large intestine and keep stool humid and soft, facilitating its passing.

The bad news is that several studies have shown that hydration alone can't cure constipation in individuals who are normally hydrated individulas. Let's look into these studies:

It is not effective

No increase in stool output in healthy hydrated subjects

Chung, Parekh, and Sellin (1999) (1) recruited 15 healthy young subjects with no history of constipation and increased their baseline fluid intake with either water or an isotonic drink (i.e. Gatorade).

Despite an increased intake of fluids (of one and two quarts - 1 and 2 liters), the study didn't find any change in stool output (urine output on the other hand did increase significantly).

The authors concluded that "Despite common medical advice to consume extra fluid for constipation, our results indicate that extra fluid intake in normal healthy volunteers did not produce a significant increase in stool output."

But what about constipated subjects?

No improvement in constipated subjects

Sun (2014) (2) found no evidence to support drinking water as a treatment for constipation: "Against common sense that drinking water is helpful for constipation, many well-known studies [...] insist that no evidence supports the use of extra fluid intake to treat functional constipation".

Tabbers (2014) (3) echoed that same opinion the study didn't find that a higher water intake was an effective treatment for constipated children.

Drinking-Water will not cure constipation unless you are dehydrated

Young, Beerman, and Vanderhoof (1998) (4) reported that small children suffering from chronic constipation did not improve even after increasing their daily water intake by 50%.

This finding was confirmed by Arnaud (2003) (5) who concluded that water therapy was not as effective as a treatment for constipation.

Extra water in pregnant women may prevent constipation

A study involving pregnant Indonesian women (Fitriana, 2018) (6) reported a "significant association between fluid intake and constipation" and concluded that "inadequate maternal fluid intake can increase the risk of constipation by 1.85 folds, and the adequate fluid intake may prevent constipation during pregnancy."

Old people can benefit from extra water intake

At least two studies (Lindeman, 2000) (7) and (Robson, 2000) (8) have concluded that in older individuals, low fluid intake is a predictor for increased levels of acute constipation.

Those consuming the least amount of fluid had over twice the frequency of constipation episodes than those consuming the most fluid.

Arnaud (2003) (5) had pointed out that not drinking enough fluids in elder subjects "was a cause of constipation". And that those who drank 500 to 2,500 ml fewer fluids (roughly 1 pint to 3 quarts) than required had a significant relationship between their liquid deprivation and constipation.

This study cautioned: "It is thus important to maintain [normal levels of hydration] as a prevention of constipation".

Water therapy is not effective in all older people

Tsindos (2015) (9) studied a group of senior citizens aged 65 and over and found that they ingested an average of 2.87 liters (3 quarts) of water daily of which 36.5% was provided by their food.

The study found that "those who self-reported no constipation consumed nearly 300 ml more water in foods than those who self-reported being constipated.".

This is roughly 1 1⁄2 extra glasses of water but, water that is in the food, not as an extra liquid intake.

Tsindos concluded: "Water consumption from food was significantly higher in those with no constipation suggesting that consumption of water in food may be a significant factor in ensuring adequate water needs".

The link with food is another option when treating constipation: An increase in fiber intake is suggested as one of the treatments for this condition.

Babies and Constipation

Babies can also suffer from constipation; in fact constipation, in infants, less than one-year-old is quite common.

So, keep an eye out for signs of constipation in babies such as discomfort or pain when they pass stools; or if they refuse to eat because they feel full or bloated. Also check out the appearance of their stools (hard, crumbly, clay-like).

This article: Baby care: how long without pooping? has plenty of useful information for anxious moms.

Fiber and Constipation

Perhaps Tsindos (10) whom we mentioned further up, has identified something beyond mere hydration by pinpointing the "consumption of water in food" as a factor that improves constipation: the combination of fiber and bulk provided by food likely contributes to the hydrating effect in the body.

Low Fiber diets may promote constipation

Murakami (2007) (10) studied Japanese women who ate a diet with very low fiber content and found that this low fiber intake coupled to a low water intake was associated with "increased prevalence of constipation".

However, Fitriana (2018) (6) who had studied pregnant Indonesian women, did not find any "significant association between fiber intake and constipation"

man holding belly, in pain
Constipation affects 20% of the world's population

A High fiber diet plus fluids help relieve constipation

Anti (1998) (11) studied 117 patients suffering from chronic functional constipation. The team divided them into two groups and gave both groups a standard diet that included 25 g (almost 1 oz.) of fiber per day.

Water intake was monitored: Group 1 consumed 1.1 liters per day (just over 1 quart), while Group 2 had a daily intake that averaged 2 liters.

The results were the following:

  • Both groups showed a "statistically significant increases in stool frequency and decreases in laxative use during the two-month trial."
  • Group 2 (which drank more water) showed greater changes compared to Grup 1 and laxative use.

Anti concluded that "A daily fiber intake of 25 g can increase stool frequency in patients with chronic functional constipation, and this effect can be significantly enhanced by increasing fluid intake to 1.5-2.0 liters/day."

Fathallah (2017) (12) favors fiber supplementation with a 20 to 25 g daily intake. Considering it "the most relevant measure [because] it improves stool frequency and consistency. It has a positive effect on excessive straining and colonic transit time".

Fiber may cause abdominal pain, flatulence, and bloating (fibers ferment in the gut) so it should be incorporated into the diet gradually for several days.

Fathallah considers additional water intake or exercising as options in special situations such as institutionalized, dehydrated, elderly, or hospitalized patients. For regular subjects, those treatments are "probably anecdotal recommendations".

Borre (2017) (13) agrees, considering that fiber, fluid, and exercise are recommendations based on scarce evidence. Nevertheless, they concede that "Increased intake of fibre will reduce colonic transit time and improve the frequency and consistency of stools in 50% of patients."

Tabbers (2011) (14) in an analysis of 9 studies covering childhood constipation (640 children) concluded that: "There is some evidence that fiber supplements are more effective than placebo. No evidence for any effect was found for fluid supplements, prebiotics, probiotics, or behavioral intervention."

Yet Jing (2012) (15), who performed a meta-analysis (a statistical procedure for combining data from multiple studies) concluded that "Dietary fiber intake can obviously increase stool frequency in patients with constipation. It does not obviously improve stool consistency, treatment success, laxative use and painful defecation."

Natural mineral water with magnesium sulfate

A review of different scientific studies by Dupont (2020) (16) reported that natural mineral water containing magnesium sulfate could be useful in treating constipation in adults.

According to Dupont, this type of water has "a laxative effect [...] in association with a very good safety profile". The subjects "all showed improved stool consistency and number of bowel movements".

Closing comments

A diet that includes adequate fiber intake (25 g daily) is a proven method for treating constipation. It can be supplemented with additional water intake to improve hydration and reach the daily intake value recommended by the National Academy of Medicine (NAM) for adults over the age of 19:

  • 91 ounces of total water for women (2.7 liters)
  • 125 ounces of total water for men (3.7 liters)

Excercise, prebiotics, and probiotics are said to help but scientific studies haven't provided evidence of their effectiveness.

References and Further Reading

(1) Chung BD, Parekh U, Sellin JH, (1999). Effect of increased fluid intake on stool output in normal healthy volunteers, J Clin Gastroenterol. 1999 Jan;28(1):29-32

(3) Sun Hwan Bae (2014). Diets for Constipation, Pediatr Gastroenterol Hepatol Nutr. 2014 Dec; 17(4): 203-208. Published online 2014 Dec 31. DOI: 10.5223/pghn.2014.17.4.203

(3) Tabbers MM et al., (2014). Evaluation and treatment of functional constipation in infants and children: evidence-based recommendations from ESPGHAN and NASPGHAN, J Pediatr Gastroenterol Nutr. 2014;58:258-274.

(4)Young RJ, Beerman LE, Vanderhoof JA, (1998). Increasing oral fluids in chronic constipation in children, Gastroenterol Nurs. 1998;21:156-161

(5) Arnaud MJ (2003). Mild dehydration: a risk factor of constipation?, Eur J Clin Nutr. 2003 Dec;57 Suppl 2:S88-95. DOI: 10.1038/sj.ejcn.1601907

(6) Fitriana, Dina & Prasetyo, Budi & Trapsila Purwaka, Bangun. (2018). Inadequate fluid intake can increase the risk of constipation among pregnant women, Majalah Obstetri & Ginekologi. 25. 48. 10.20473/mog.V25I22017.48-53

(7) Lindeman RD et al. (2000). Do elderly persons need to be encouraged to drink more fluids?, J Gerontol A Biol Sci Med Sci. 2000;55:M361-365

(8) Robson KM, Kiely DK, Lembo T, (2000). Development of constipation in nursing home residents, Dis Colon Rectum. 2000;43:940-943

(9) Tsindos, P. S., Itsiopoulos, C. and Kouris-Blazos, A., (2015). Investigation into water consumption and its influence on depression, memory problems and constipation in older persons, Journal of aging research & clinical practice, vol. 4:3 137-143, DOI: 10.14283/jarcp.2015.65

(10) Murakami K, Sasaki S, Okubo H, et al. (2007). Association between dietary fiber, water and magnesium intake and functional constipation among young Japanese women, Eur J Clin Nutr. 2007;61:616-622

(11) Anti M, et al. (1998) Water supplementation enhances the effect of high-fiber diet on stool frequency and laxative consumption in adult patients with functional constipation, Hepatogastroenterology. 1998 May-Jun;45(21):727-32

(12) Fathallah N, Bouchard D, de Parades V., (2017) Diet and lifestyle rules in chronic constipation in adults: From fantasy to reality..., Presse Med. 2017 Jan;46(1):23-30. DOI: 10.1016/j.lpm.2016.03.019. Epub 2017 Jan 5

(13) Borre M. et al., (2015). The effect of lifestyle modification on chronic constipation, Ugeskr Laeger. 2015 Apr 6;177(15): V09140498

(14) Tabbers MM, Boluyt N, Berger MY, Benninga MA., (2011). Nonpharmacologic treatments for childhood constipation: systematic review, Pediatrics. 2011 Oct;128(4):753-61. DOI: 10.1542/peds.2011-0179. Epub 2011 Sep 26

(15) Jing Yang, Hai-Peng Wang, Li Zhou, and Chun-Fang Xu, (2012). Effect of dietary fiber on constipation: A meta analysis, World J Gastroenterol. 2012 Dec 28; 18(48): 7378-7383. DOI: 10.3748/wjg.v18.i48.7378

(16) Dupont C, Hérbert G. (2020). Magnesium Sulfate-Rich Natural Mineral Waters in the Treatment of Functional Constipation-A Review. Nutrients. 2020;12(7):2052. Published 2020 Jul 10. DOI:10.3390/nu12072052.

About this Article

Water intake and Constipation, A. Whittall

©2018, 11 Oct. 2018. Updated. 23 Oct. 2020.

Tags: constipation, Dehydration, 8 x 8 rule, hydration, water requirements, daily water intake.

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Subject: Constipation and Water intake. Do extra hydration and water intake cure constipation?

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