Is tap water in Thailand actually good for your skin?

No, I don't want to talk about the (usually chlorinated) tap water in Bangkok, but about the water that you can pump yourself or get from a water supply network of the village where you live, so untreated groundwater or water that has only minimal treatment got. This in response to a response to Thailandblog from a few months ago where I was too late to respond.

The response stated, among other things, that:

“Recently my wife got the results of her well water. Must be inspected before use. Turns out her water has a pH of 4.8 (approved by Thai research lab !!??), so it's quite acidic and isn't good for any metal material, not for your tiles and not for you either.

You can check yourself with pH strips and see how acidic your water is, doesn't cost much. So now have to consider bringing this pH value to 7, neutral. Not really working on it yet, but thinking about an ion exchanger, a filter filled with resin. Still need to put in a few filters, because it's not always clear. A real RO filter would be great, but costs more and the production process would also cost quite a bit. For 1 glass of water, 4 thrown away, well, let's take a look.

No idea what city water is like in Thailand, as pH 4,8 is approved. But acid does attack all kinds of materials, except plastic. Why all the plastic pipes in Thailand? It is also cheaper of course.

The use of acid water can cause problems with your skin and your hair (can break off) over time, but yes, people also go for a chemical peeling. You don't need it anymore if you shower every day. It is therefore best to use plastic taps, but water is still too acidic for you.”

Well, I can reassure the writer, water of pH 4,8 is not bad for your skin and not bad for your hair, but good. Now that of course requires some explanation because I don't assume that the writer just takes it from me.

First of all, it is of course not such a strange idea that acid would be bad for your skin, because Dutch tap water is slightly alkaline with a pH that is usually around 8. Moreover, with a pH of 7,4, your blood is also not acidic but slightly alkaline. Furthermore, your teeth are known to be affected by lactic acid formed by bacteria and fruit and phosphoric acid from soft drinks. Your eyes also prefer not to come into contact with acid; your tear fluid has a pH of approximately 7,4. But your skin? It wants to be slightly acidic and fortunately it is if the skin does not come into contact with alkaline tap water too often.

Dutch tap water is not "natural" but undergoes many treatments and the pH is also artificially raised to a relatively high level, otherwise lead and copper and other metals would dissolve and pose a threat to public health. It is definitely not made alkaline to spare your skin.

But why is it that (the surface of) untreated skin has an average pH of 4,7? After washing with slightly alkaline (Dutch) tap water, your skin has a pH close to 6. But the sweat that ends up on your skin - even if you don't sweat noticeably - has a pH of 5 to 6 and contains ammonium lactate. And that ammonium lactate causes a sharp drop in pH to sometimes as much as 4 because it splits into ammonia and lactic acid on the skin. The ammonia volatilizes but the lactic acid remains on your skin and provides the desired pH drop. Desirable, because such acidic skin is usually in a better, healthier condition than skin that is less acidic.

This is especially evident with people who suffer from eczema. The skin pH of those people is on average somewhat higher than people without eczema and the affected skin in particular has a high pH. And that higher pH is optimal for Staphylococcus aureus (optimal pH for this "flesh-eating" bacteria is 6-7) which occurs in 90% of cases in eczema patients (and only 5% in others). A high skin pH gives Staphylococcus aureus the chance to colonize the skin and if the skin becomes damaged it results in an infection and what is worse, the bacteria then enters the deeper layers of the skin where the pH is naturally 6-7 . Once there, the bacteria is almost impossible to get rid of: eczema!

A low skin pH has a second advantage, namely that the bacteria Staphylococcus epidermidis naturally occurring on the skin and harmless under normal circumstances have favorable living conditions. This bacterium is even capable of creating its own acidic system by, among other things, converting the glycerol present on the skin into acid. Fortunately, S. epidermidis helps our bodies defend against S. aureus. S. epidermidis even has a secret weapon for this: serine protease Esp. This is an enzyme that can inhibit the growth of S. aureus. Incidentally, there are of course many more factors that play a role in eczema, but that is not relevant for this story.

Eczema will be more common in the Netherlands than in Thailand because the tap water in the Netherlands is alkaline and because there is less sweating than in Thailand. Fortunately, most people in the Netherlands do not have any problems, but that is because in most cases the skin pH drops below 5 within a few hours after a shower. However, there are unlucky people who sometimes need 48 hours for this and if they take a shower every day, their skin pH never falls below 5.

But why is the (pumped) water in Thailand so acidic? However, not all groundwater in Thailand is acidic because it depends on the composition of the rainwater and also on the composition of the soil. And, by the way, also the amount of sunshine.

Rain is “saturated” in carbon dioxide (in equilibrium with carbon dioxide in the atmosphere) and therefore normally has a value of 5,6. Light sour. In an industrialized environment or an environment with a lot of traffic, nitrogen oxides and sulfur oxides can also dissolve in the rain. And those oxides form nitric acid and sulfuric acid in the raindrop. You then get the acid rain that they were so afraid of in the Netherlands 50 years ago. Rightly afraid, but of course also a bit exaggerated (predictions of dying forests, etc.). The pH of that rain was therefore much lower than the natural value of 5,6.

In Thailand, the pH of rainwater will also fall below 5 locally, but I am not aware that this causes problems in nature (in China, for example, the situation is slightly different). Once on earth, the pH can drop even further if, for example, organic acids are formed through the decomposition of organic material. But if calcium carbonate is present in the soil, calcium bicarbonate is formed and this reaction has a neutralizing effect. And sunlight? Sunlight ensures that carbon dioxide in surface water is scavenged by algae, which can cause the pH to rise. In the Netherlands, with its long days in the summer, the pH of surface water can rise to 10 in the afternoon in exceptional cases. This will probably not happen in Thailand due to the shorter days. However, this makes it clear that groundwater, also in Thailand, can be both acidic and alkaline.

In the case described, the pH of the pumped water was 4,8, so it contains more than just carbon dioxide. I'm betting on organic acids. And that could indicate that the water is pumped up from a relatively shallow depth and that it may also contain the necessary bacteria. In fact, extensive research is needed into the chemical and bacteriological composition, but your eyes (colour, turbidity), nose and taste buds will of course also tell you a few things. My wife just drinks our pumped water, but that comes from a depth of 30 meters where there is also a water impermeable layer of about 10 meters. That indicates that the water has come a long way. Our water is neutral and clear. I'm not taking the risk myself.

A different story applies to your hair, but even then a pH lower than 6 is good because then the scales close. You then get smoother, shinier hair that also retains virtually no dirt. You don't actually need an (acidic) conditioner anymore. In the Netherlands, unfortunately.

And your taps? That will also work out.