Thermal water does appear to benefit skin, particularly for people with inflammatory conditions like psoriasis and eczema. The evidence is strongest for bathing in mineral-rich thermal springs, where clinical trials consistently show measurable improvements in symptoms. The popular spray-can versions sold by skincare brands have less robust evidence behind them, but their mineral content can still soothe irritation and support the skin’s protective barrier.
What Makes Thermal Water Different From Tap Water
Thermal spring water picks up minerals as it filters through underground rock over hundreds or thousands of years. The result is water with a specific, consistent mineral profile that ordinary tap water doesn’t have. A well-studied example, La Roche-Posay thermal spring water, contains 149 mg/L of calcium, 387 mg/L of bicarbonate, 31.6 mg/L of silicate, 4.4 mg/L of magnesium, and trace amounts of selenium, strontium, and zinc. Its pH sits right at 7, which is neutral and close enough to the skin’s slightly acidic surface (around 4.5 to 5.5) to avoid disrupting it.
These minerals aren’t just dissolved solids. Selenium acts as an antioxidant, helping protect skin cells from damage caused by UV exposure and pollution. Silica supports the structural proteins that keep skin firm. Calcium plays a role in how skin cells renew themselves. Bicarbonate helps buffer pH. The specific combination and concentration varies by spring, which is why different brands have different properties. Research suggests that thermal waters with lower total mineral content (under 1 g/L of dissolved solids) tend to produce greater improvements in skin softness and comfort compared to more heavily mineralized waters.
Clinical Evidence for Psoriasis and Eczema
The strongest clinical evidence for thermal water comes from bathing treatments, often called balneotherapy. A systematic review covering eight studies found that every single one reported clear improvement in signs and symptoms of psoriasis or eczema after thermal mineral water baths. That’s a remarkably consistent result across different springs, study designs, and patient populations.
The improvements are measurable, not just subjective. Multiple studies tracked standardized severity scores and found significant reductions after treatment. One trial of 77 patients with mild to severe psoriasis showed that even one week of thermal water bathing reduced symptom severity by about 11.5%, with two weeks producing a roughly 13.5% reduction. Patients also reported better quality of life and less anxiety and depression related to their skin condition. One study combining thermal baths with light therapy found the combination worked better than light therapy alone, suggesting thermal water adds a real therapeutic benefit beyond relaxation.
For eczema, a controlled study comparing thermal water baths to regular tap water baths found that while both groups improved, patients using thermal water improved significantly more. Skin moisture increased rapidly after thermal water bathing, which is especially relevant for eczema, where a compromised skin barrier leads to chronic dryness.
There is one important caveat. In one trial, patients who improved during treatment gradually returned to their baseline condition over the following three months. This suggests thermal water bathing manages symptoms rather than curing the underlying condition, and repeated courses of treatment may be necessary to maintain results.
How Thermal Water Supports the Skin Barrier
Your skin’s outermost layer acts as a shield, keeping moisture in and irritants out. When this barrier is damaged, whether from harsh products, dry air, or conditions like eczema, skin becomes red, dry, and reactive. Thermal water appears to help repair and reinforce this barrier in a few ways.
The minerals in thermal water support the enzymes and proteins your skin needs to maintain its structure. Calcium, for instance, is essential for the process by which new skin cells mature and move to the surface, forming a tighter, more resilient barrier. The rapid increase in skin moisture seen in clinical studies suggests thermal water helps the barrier hold onto water more effectively. A double-blind study comparing spring water from Comano, Italy, to regular tap water confirmed that the mineral content itself drives this effect, not just the act of wetting the skin.
Effects on the Skin Microbiome
Your skin hosts a community of bacteria, fungi, and other microorganisms that play a surprisingly important role in keeping it healthy. A diverse skin microbiome helps defend against harmful bacteria, regulates inflammation, and supports the skin barrier. When that diversity drops, problems like acne, rosacea, and eczema tend to get worse.
Thermal spring water naturally contains prebiotics and probiotics, the same types of beneficial microorganisms and the compounds that feed them. Preliminary research suggests that applying thermal water to the skin may help shift the microbiome toward greater diversity. An expert panel reviewing the evidence concluded that topical prebiotics and probiotics, including those found in thermal spring water, may improve signs of skin aging by supporting a healthier microbial balance on the skin’s surface.
Spray Products vs. Thermal Baths
Most people encounter thermal water not at a European spa but in an aerosol can from the skincare aisle. These sprays contain real thermal spring water, bottled at the source, so the mineral content is identical to what you’d find at the spring itself. The difference is in how you use them: a quick mist delivers far less exposure than soaking in a thermal bath for 20 minutes.
That said, thermal water sprays have practical uses. They can calm skin after sun exposure, reduce redness after a procedure like a chemical peel, refresh skin during flights or in dry environments, and set or soothe skin after applying other products. Many dermatologists in Europe recommend them as a gentle, fragrance-free way to hydrate reactive skin. The key is to either pat the water into your skin or follow up with a moisturizer. Letting it air-dry on its own can actually pull moisture away from the skin as it evaporates.
What Thermal Water Won’t Do
Thermal water is not a replacement for active skincare ingredients. It won’t treat acne the way a retinoid or salicylic acid would, and it won’t reverse sun damage or deep wrinkles. Its strength is in calming, hydrating, and supporting the skin’s natural defenses. Think of it as a complement to your routine rather than the centerpiece.
For people with healthy, non-reactive skin, the benefits are subtle enough that you may not notice much difference compared to regular water. The people who tend to see the most noticeable results are those with compromised skin barriers, chronic inflammation, or conditions like psoriasis and eczema, where the anti-inflammatory and barrier-supporting properties of the minerals have more room to work.