How does shower water pH affect the skin: what does science say?

We often pay attention to the pH of our creams, cleansers, or soaps, but rarely stop to think: what is the pH of the water we use to wash our face or take a shower? Yet water is what comes into contact with our skin most frequently. Alkaline water, also known as high pH water, can disrupt your skin's delicate acid mantle, having a significant impact on overall skin health—often leading to dryness, irritation, and premature aging.

pH is a measure of acidity. It’s measured on a scale from 0 to 14:
0−6 — acidic
7 — neutral
8−14 — alkaline
The normal pH of healthy skin ranges from 4.7 to 5.5.
This means the skin is naturally slightly acidic. This environment supports:

• The protective barrier (acid mantle)
• Microbiome balance
• Anti-inflammatory defense
• Moisture retention

If the pH of water differs from this range — especially if it’s more alkaline — it can disrupt the skin’s natural barrier.

Most municipal water systems supply water with a pH between 7 and 8.5 — meaning it is neutral or slightly alkaline. This is done to protect pipes from corrosion, but it's not necessarily good for your skin.
A study published in the International Journal of Cosmetic Science (2006) showed that even brief contact with alkaline water raises the skin’s pH, makes it drier, and disrupts the lipid barrier.
Source: Lambers et al., “Natural skin surface pH is on average below 5, which is beneficial for its resident flora”

You might wonder why municipal tap water often has a pH above 7. The answer lies directly in its mineral content. Tap water is rarely just pure H2O; as it is sourced and treated, it naturally contains various dissolved minerals, primarily calcium and magnesium.
When water contains high levels of these specific minerals, it is commonly referred to as hard water. Because calcium and magnesium are naturally alkaline substances, they actively raise the water's pH level. In short: the more mineral-rich your tap water is, the more alkaline (high pH) it becomes.
This is a crucial connection for your skincare routine. If you live in an area with hard, mineral-heavy water, you are essentially washing your face and showering in alkaline water every single day. Not only can these minerals leave a microscopic residue on your body, but their high pH directly attacks your skin's natural acid mantle, setting the stage for dryness and irritation.

If you regularly shower or bathe in water with a pH above 7, it can lead to:

• Damage to the skin’s acid mantle
• Increased dryness, tightness, and flaking
• Disruption of the microbiome (growth of “bad” bacteria and fungi)
• Worsening of inflammation and itching in conditions like eczema, rosacea, or psoriasis

The Journal of Investigative Dermatology (2001) notes that restoring the skin’s acid balance after washing with water at pH 8 can take up to 6 hours, especially for people with dry or mature skin.
Source: Schmid-Wendtner & Korting, “The pH of the skin surface and its impact on the barrier function”

Ideally, shower and bath water should have a pH of 5.5–6.5. This slightly acidic range is much closer to the skin's natural level and ensures that your protective barrier remains intact. According to a 2017 review published by Ananthapadmanabhan et al. in the International Journal of Women's Dermatology, washing with water and products that match the skin's natural pH significantly improves moisture retention and effectively reduces symptoms of atopic dermatitis and acne.

Not everyone can change the composition of their tap water, but there are a few simple solutions:

• Shower filters.
• Acidic body sprays or rinses after showering. These help restore the skin’s acid mantle, especially for sensitive or dry skin.
• Gentle, pH-balanced cleansers. Choose body washes and facial cleansers with a pH of 5–5.5 — this is especially important if your local water is hard and alkaline

We carefully choose skincare products based on our skin type, but often overlook the most obvious factor — the water we use every day. If its pH doesn’t match the skin’s needs, no cosmetic product can fully prevent dryness, irritation, or discomfort.
Start with the basics — check the pH of your water. It could make a noticeable difference in your skin’s condition within just a few days.