It is not yet known whether alkaline water can help treat or prevent cancer. The theory suggests that this is because cancer cells thrive in an acidic environment. However, excessive consumption can have health consequences.
Even tap water has a pH level of around 7.5. Alkaline water consumes a pH of 8 to 9. The higher the sum, the more alkaline (basic) it is; the lower the number, the more acidic it is.
Below, we present what you need to know about the likely benefits and risks of alkaline water in treating cancer.
Alkaline Water and Cancer
Alkaline water is said to help counteract acidity in the bloodstream. Proponents of this idea believe that drinking water with a higher pH speeds up metabolism and improves the body’s ability to absorb important nutrients.
Some theorise that this starves the body’s cancer cells of nutrients, since they thrive in an acidic environment. Introducing alkaline substances is said to slow or stop cancer growth by balancing the body’s pH levels.
Alkaline water can hydrate the body. For some people, it can also relieve symptoms related to acid reflux.
However, if your body is functioning normally, alkaline water will not cause much change—if any—in your bloodstream’s overall acid-base balance.
What the research says
There is limited scientific evidence and few clinical trials supporting the use of alkalizing therapies—such as an alkaline diet or alkalizing agents—to treat or prevent cancer. There is no scientific evidence to support their effectiveness in humans.
Additionally, it is almost impossible to significantly alter your blood pH by consuming specific foods or fluids. The body naturally balances its internal pH level without requiring significant intervention or conscious effort on your part.
Cancer should not significantly affect your overall pH level. While tumour cells can produce lactic acid, it is generally insufficient to alter the body’s pH.
While alkaline water can contribute to a better pH balance, excessive alkalinity can also be harmful to the body.
How to Consume Alkaline Water
In 2026, the World Health Organisation (WHO) published efficient guidelines on the quality of drinking water.
These guidelines state that, in general, pH levels do not directly affect human health. Disinfected water treated with chlorine should have a pH below 8.0.
If you want to drink alkaline water, you can drink it just like you would regular tap water. However, consuming too much alkaline water can lead to side effects.
Risks and side effects of too much alkaline water
Your figure is not designed to survive on alkaline water alone. While there is no evidence to show that alkaline water is harmful, excessive consumption can interfere with stomach acid production. This can lead to:
- indigestion
- stomach ulcers
- nausea
- vomiting
In addition, stomach acidity is essential for many bodily processes.
If you have kidney disease or a chronic kidney-related condition, consult your doctor before drinking this type of water.
Where can I get Alkaline Water?
You can make your own alkaline water using special filters or taps, or you can use additive drops to make the water alkaline.
You can buy water ionisers that alter tap water to give it an alkaline pH. Additionally, bottled alkaline water is available at most supermarkets.
Scientific evidence does not support the claim that alkaline water has a positive effect on cancer or overall health. As a result, your health insurance provider will usually not cover the cost of alkaline water; however, we recommend contacting them to confirm.
Conclusion
While alkaline water is generally careful safe to drink, there is no evidence to support its use for general health or as a beneficial aid in cancer treatment.
If you decide to try alkaline water, here are some tips:
When metabolised, it produces alkaline byproducts that raise urine alkalinity.
If you decide to make your own alkaline water, use distilled water. This will help reduce the amount of additives present.
Avoid drinking alkaline water while eating. Drinking alkaline water with food can negatively affect your body’s digestive process.
If you experience any unusual side effects, discontinue use and consult your doctor. They can help you control the cause and, if necessary, adjust your treatment plan.