Water Is Bad For Your Skin?! – Skin pH & Acid Mantle

In this post:
Why pH Matters
What affects the pH
Lemon & Baking Soda should stay in the kitchen


Why pH Matters

Let’s get the boring stuff out of the way first –

pH measures how “acidic” or “basic” a particular substance on a scale between 1 – 14, with 1 being very acidic, and 14 very basic. And in the middle of that scale is pH 7 which is neutral. So, if I were to compare lemon juice (pH 2) and baking soda (pH 9), lemon juice is acidic and baking soda is basic. And water (pH 7) is neutral.

If it helps you understand better, anything ‘sour’ is usually acidic and anything bitter is usually basic or alkaline.

Most things we put on our skin has a pH, including our skin itself.


Acid Mantle is a layer of acidic fluid left behind on the skin when sweat evaporates (yes, you still sweat a tiny bit even when it’s cold but it’s good sweat!)(1). Acid mantle is what gives our skin its pH and it is where the healthy skin bacteria (microflora or cutaneous bacterial flora) live. It is our body’s defence mechanism to protect our body from external bacteria.

A healthy skin has a pH of about 4.7 which makes it acidic – NOT neutral (2). I know, I was surprised too when I first found out. Naturally, anything that we put on our skin that has a different pH, affects the pH of our skin and consequently, the acid mantle.

Researchers found that the processes that goes on in our skin, those that repair the skin and keeps the skin healthy requires an acidic environment to function properly. Skin with pH above 5 was found to cause dispersion in healthy bacteria (4) and impaired barrier function which leads to all sorts of skin problems ranging from acne (9), dryness to more serious problems like dermatitis.


Here’s one that looks promising – in one study, acne patients treated with low pH cleansers show great reduction in acne. Why? The strain of bacteria that causes acne does not thrive in acidic conditions (7,8). 😎



  1. Our skin is acidic (pH 4.7)
  2. We want to keep it acidic to be healthy – keep acid mantle intact
  3. Acid mantle is badass
  4. Things we put our skin may affect its pH and integrity of the acid mantle


Skin pH & Acid Mantle - pH scale
Source: http://www.edu.pe.ca/gulfshore/Archives/ACIDSBAS/scipage.htm


What affects pH of the skin

Basically anything that touches it – including water (3). The rule of thumb is, the higher the pH of the substance, the more it changes the pH of the skin, the more it disrupts the acid mantle (3). Take hard water (pH 8), for example, is more disruptive to the skin than regular tap water (pH 7). Don’t panic just yet!


You Have Bigger Problems

Your cleanser. (6)

You know that squeeky clean feeling that you get after you wash your face? And then you pat dry and it feels tight? Yeah, that’s actually not good. That’s the acid mantle being disrupted.

A good cleanser removes excess oils, makeup residue, dirt and external pollutants and leaves behind oils that are essentially part of the skin. The skin does not like it’s border being infiltrated.

This is why oil cleansing is amazing – oils have no pH. But this doesn’t mean that all non-oil cleansers are bad. Some cleansers are formulated to have low pH. A common one is pH 5.5 like this Sebamed one. More on how to choose a cleanser in another post soon!


I came across a weird study (by weird, I mean disturbing!😷) done on infants between 2 weeks to 16 months where they test the effects of different pH cleansers on their skin (5). They found that skin treated with higher pH cleansers increases the pH of skin and decreases the fat content i.e. disturbs the acid mantle.


Funny story. I remember when Johnson & Johnson released a pH 5.5 body wash years ago claiming that it was a good pH to neutralise the skin. I scoffed and blew it off as a gimmick. Yeah, foot in mouth.


Baking Soda and Lemon

They should stay in the kitchen.

Skin pH & Acid Mantle - Lemon & Baking Soda Effects
Source: https://steptohealth.com/4-best-benefits-baking-soda-and-lemon/


If water, something that has pH 7 already affects the pH of our skin, imagine what baking soda (pH 9!!) does to it! 🤕 This is why you should NEVER put baking soda on your face.

“Oh, I’ll add more water, that’ll make it gentler”. Nope. Put it back in the pantry, it’s not going near your face.


Similarly, you should NEVER put lemon on your skin. Lemon juice (5% citric acid) has a pH of 2 which is highly acidic. Don’t confuse this with the acids used in chemical exfoliation. Acids can potentially be very damaging so formulation of topical chemical exfoliants are highly regulated. Those available to purchase are usually pH 4-5 are safe to be used on the skin. 


I’ll be discussing the effects of pH on chemical exfoliants in another post soon.


So save that lemon for your tequilla.



  1. Stuff with too high or too low pH affects the pH of the skin adversely and disrupts the acid mantle.
  2. Oils don’t have pH – they’re good.
  3. Lemons are for lemonade and baking soda is for well, baking. Keep them that way.
  4. Watch out for next posts on how to choose the right cleansers & pH dependent products and when to use them


Shameless plug: Sign up to my newsletter to stay updated to when those posts go live and you’ll also get a basic guide to build an effective skincare routine – free of charge.

But really, I hope that this article has at least helped you figure out if your cleanse has been sabotaging your skin so share this and see if your friend’s cleanser is sabotaging them.


1 https://books.google.ie/books?id=AWEDzXOAivgC&pg=PA31&redir_esc=y#v=onepage&q&f=false

2 http://onlinelibrary.wiley.com/doi/10.1111/j.1467-2494.2006.00344.x/full

3 http://www.karger.com/Article/Abstract/245955

4 https://www.ncbi.nlm.nih.gov/pubmed/141301

5 http://www.karger.com/Article/Abstract/245955

6 http://www.sebamed.es/fileadmin/pdf/1.06.pdf

7 https://www.ncbi.nlm.nih.gov/pubmed/141301

8 http://link.springer.com/article/10.1007/BF01833872


Get on your way to Clear Skin

Get new content delivered to your inbox & get a FREE skincare guide!

Powered by ConvertKit