Is distilled water acidic and does it harm you?

Written by William Fryer - MA Oxon

One of the really hot topics which you see a lot of people talking about with regard to distilled water is acidity. The theory goes that because distilled water is very mildly acidic it can leach minerals from the body. There is also a competing theory that slightly different theory that the acidity of distilled water makes the body ultimately more alkaline. And there are many advocates of drinking alkaline water. Anyway, let’s now examine the scientific basis for this.

Distilled water at the moment of distillation is pH7 which is neutral. Then, after a relatively short time a very small amount of the distilled water will bond with atmospheric carbon dioxide to make a very small amount of carbonic acid, much less than you would get with a carbonated drink for example but enough to push distilled water to pH6. That is about the same as most fish meat, asparagus, butter, olives or a curry. With the pH scale lower is more acidic and it is also logarithmic. What that means is that ph6 is 10x more acidic that pH7, ph5 is 100x more acidic than pH7, pH4 is 1000x more acidic than pH7, etc. Something really acidic like Coca Cola (and most fizzy drinks) is pH 2.5. Your stomach acid is pH1.5 to 3.5. The acidity of a car battery is about pH0.7 - 1.0. So you can see, yes distilled water is technically acidic, but really not by very much. Now what happens in your gut?

When you swallow anything it triggers the release of hydrochloric acid into the stomach and part of the job of that acid is to kill off any bugs that might be in your food. Next stop after the stomach is the duodenum and at this stage lots of bicarbonate gets released into the food to neutralise the pH and from then on the food gets absorbed during its passage through your intestines. People have two main worries:

First, they worry that drinking distilled water will make their stomach contents more acidic. Let’s think about this, when you pour a very weak acid (distilled water) into a very strong acid (stomach) you end up with a diluted (less acidic) mixture. To make your stomach more acidic you would need to be consuming something more acidic than the stomach contents. Drinking distilled water is never going to make your stomach contents more acidic, it will only ever make it less acidic.

Secondly, people worry that drinking distilled water will somehow make their bloodstream more acidic and that this will leach minerals from their bodies. Drinking distilled water is not going to make your blood stream more acidic. After the water has been mixed with the incredibly strong acid in your stomach and then mixed with the alkalising effect of the bicarbonate, any latent acidity that might have existed in the distilled water will have been completely wiped out.

The whole leaching minerals argument is an example of what is called psychologists call truthiness; it kind of sounds like it could be true so people believe it. In reality it is non-science. Your body works extremely hard to keep your blood pH between 7.35 and 7.45. If it goes outside that range then your enzymes start to denature and you need to go to hospital (in an ambulance). Even people who are slightly out of range like pH7.25 can be very ill indeed. For your blood to be acidic enough to actually start dissolving minerals it would have to be well below pH6 and you would definitely be long dead by then. In addition minerals are held in bone in a complex organic molecule called hypoxyapetite, it's a combination of Vitamin D and Calcium, you need enzymes to get the Calcium out - not acid.

The idea of acidic water sounds scary but it does not harm you, if it could, rainwater would harm you and most foods would harm you. There is nothing harmful about drinking distilled water. And if you are at all worried about it being mildly acidic then you can always add a pinch of Sodium Bicarbonate to rebalance the pH.

The whole leaching minerals argument is an example of what is called psychologists call truthiness; it kind of sounds like it could be true so people believe it. In reality it is non-science. Your body works extremely hard to keep your blood pH between 7.35 and 7.45. If it goes outside that range then your enzymes start to denature and you need to go to hospital. Even people who are slightly out of range like pH7.25 can be very ill indeed. For your blood to be acidic enough to actually start leaching minerals it would have to be well below pH6 and you would definitely be long dead by then.

You can make your distilled water more alkaline by adding say Sodium Bicarbonate to it. Alkaline water has a higher pH (above pH7). Some people claim that drinking alkaline water can help prevent disease, such as cancer and heart disease. However, there isn't enough research to verify these claims and there is no evidence that alkaline water is better than any other type of water. There are suggestions of potential risks from alkaline water. In a study, baby rats given alkaline water showed impaired growth and damage to cardiac muscle. Additionally, a case report released in 2015 said that when a municipal water plant in a town in Germany accidentally increased the water’s pH to 12, skin burns ensued.