Alkaline water is the opposite of acidic water. It has a higher pH level than plain water.

Claims of health benefits have helped increase the popularity of alkaline diets and sales of machines that turn water alkaline. Ionizing machines are one example of these products, which can cost over a thousand dollars.

But what scientific evidence lies behind drinking alkaline water? Are there any proven health benefits?

Contents of this article:

    What is alkaline water?
    Alkaline water and bone health
    Alkaline water and cancer
    Alkaline water and acid reflux
    Summary of health benefits to drinking alkaline water
    Why is hydration important?

What is alkaline water?

Alkaline water has a high pH:

    Neutral is a pH of 7.0
    Regular water from rainfall is usually slightly acidic, just below neutral on the pH scale
    Acidic, or basic, water is below a pH of 7.0, down to zero
    Vinegar is around pH 3, lemon juice is around pH 2, and battery acid is around pH 1
    Alkaline water is above pH 7
    Baking soda is between pH 8 and 9, and Milk of Magnesia is between pH 10 and 11

The pH of water is changed by chemicals and gases. Carbon dioxide from the air increases acidity, for example. This is why rainwater's pH is below neutral.

Water that is too high or too low in pH has adverse effects. Water that is too alkaline has a bitter taste. It can cause deposits to encrust pipes and appliances. Highly acidic water may corrode metals or even dissolve them.
How to get alkaline drinking water

Machines called ionizers make water alkaline, but they are expensive.

Bottled mineral water tends to be neutral or slightly alkaline. Some manufacturers may state the pH level of their bottled waters.

Sparkling waters are acidic. Carbonation introduces carbon dioxide, which lowers the pH.
 
Alkaline water and bone health
 
Some research has been done into effects of alkaline intake on bones. A study published in Bone found an effect on bone resorption. Bone resorption is the process where old bone cells are broken down and replaced by new ones.

Less bone resorption and more mineral density result in better bone strength.

The study examined a very small number of people, though. Only 30 women took part in the research.

The authors concluded "that a bicarbonate- and calcium-rich alkali mineral water decreased bone resorption more than a calcium-rich acidic mineral water."

They called for more work to be done, to see if the benefit of less bone resorption was long-term and could improve bone mineral density.

Large review of evidence

Another study, published in Nutrition Journal, looked at an alkaline diet rather than alkaline drinking.

The review looked into whether an acidic diet could cause osteoporosis, a disease marked by weak and brittle bones.

Reviewing the background to the study, the authors noted a high number of claims being made on the Internet. These claims suggested "that alkaline diets and related commercial products counteract acidity, help the body regulate its pH, and thus prevent disease processes."

The review used high-quality evidence to conclude that acid from the modern diet does not cause osteoporosis. It also concluded that an alkaline diet or alkaline supplements or salts do not prevent osteoporosis.
Alkaline water and cancer

A review of the effects of alkalis on cancer was published in the journal BMJ Open.

The review assessed thousands of studies. However, the authors found only one proper, randomized test of acid in the diet and cancer of the urinary bladder.

They found no studies about alkaline water and cancer in humans. The review did find some other types of study of alkaline water, "none of which supported the promotions that suggest alkaline water supports good health."

They found only harms from alkaline water, including:

    Restricting the release of stomach acids
    Reducing gall bladder emptying
    Poisonous reactions
    Heart problems

The alkaline diet, said the authors, is promoted to correct "the acid state that the modern diet creates." The alkaline diet includes more fresh fruits and vegetables and reduced protein intake.

"The marketing of the alkaline diet promotes not only a diet, but also the sale of related supplements and water alkalinizer machines through almost every media medium, including websites, books, and videos," the authors wrote, adding:

"In our experience, patients with cancer are approached by salespeople who are promoting water alkalinizers as a way to treat their cancer."

The overall conclusion of the paper was there was no evidence to support the use of the alkaline diet:

    "Despite the promotion of the alkaline diet and alkaline water by the media and salespeople, there is almost no actual research to either support or disprove them."

Alkaline water and acid reflux

 Acid reflux disease is when the contents of the stomach, which are acidic, splash back up the food pipe.

Acid reflux that keeps happening for a long time can cause damage and a disease known as gastroesophageal reflux disease, or GERD.

A study published in Annals of Otology, Rhinology & Laryngology found that drinking alkaline water might be worth further study as a supplement to other treatment for reflux disease.

It found that alkaline water at pH 8.8 stops an enzyme that is connected to reflux disease. It also appeared to reduce the acidity of the stomach contents.

The work was done in a laboratory rather than in humans. More research would be needed to support these findings.
Summary of health benefits to drinking alkaline water

There is no good evidence that drinking alkaline water is good for health or treats any medical conditions.

It may be wise to think twice about claims that alkaline diets or water are especially good for people.