Skin barrier prevents the growth of pathogenic bacteria
The skin protects the human body from its environment. One of the important characteristics of skin is it's surface pH which is largely acidic and is around 5.5. The skin is a habitat for a complex microbial ecosystem. Permanently resident good bacteria act as a defensive barrier and prevent the growth of pathogenic, or bad bacteria.
Changes in skin pH level and use of antimicrobial skin cleansers may compromise the barrier
We normally think that washing our skin more frequently is a good thing. But be wary that intensive use of antimicrobial skin cleansers could lead to an increased susceptibility to skin infections. This is due to the fact that the normal flora of the skin gets invaded, so do not forget that you need to think about your good bacteria not only bad.
Normal soap has alkaline pH, which is a lot higher than pH of the skin. After washing our skin with soap, our skin's pH temporarily goes up, which creates a favourable environment for pathogenic bacteria.
Also, we often hear that natural is better than synthetic, however, some people may prefer synthetic cleanser due to the fact that synthetic cleansers usually have pH that matches the skin. This may be particularly relevant for acne prone individuals to keep P. acnes bacteria at bay.
Tap water in Europe has a pH level of around 8 which is a lot higher than acidic skin surface pH of around 5.5. Washing ourselves under tap water temporarily increases skin pH level even if we use a cleanser that is balanced. If skin is left unwashed and unaltered by any chemicals for 24 hours, its natural level of pH drops to around 4.9.