AutHOR'S NAME: RENATA SANZI

Physico-chemical analysis of thermal waters: the chemist's perspective

Dott. Renata Sanzi
Pharmacist and Medical Communication Specialist - Italy

In this session, we’ll focus on the physicochemical properties of thermal waters, focusing on their origin, composition, and remarkable benefits.

For millennia, from Hippocrates to the Roman emperors, thermal springs have been revered as natural health temples, places where humanity reconnects with the Earth's primordial power. Today, we will explore their extraordinary physicochemical properties, uncovering how this ancient alchemy unfolds.

Thermal waters are far more than just hot streams; they are the result of a deep and powerful interaction between geological forces and the hydrological cycle. Geology acts as the furnace: it provides the geothermal heat source and the subterranean fractures that allow water to undertake an epic, pressurized journey deep underground. It is here, far from the surface, that water is transformed, becoming enriched with dissolved minerals and gases that define its unique therapeutic signature.

Temperature is the most defining feature — the true chemical engine of the thermal system.

As temperature increases, the solubility of minerals and gases rises, altering both the composition and properties of the water.

This explains why hotter springs are often richer in silica, sulfur, and mineral salts.

The physical properties — such as density, viscosity, and thermal conductivity — also change with temperature, influencing the dynamics of geothermal flows.

From a therapeutic perspective, the key lies in the water’s chemical structure. The unique ratio of major cations and anions (sodium, calcium, chloride, sulfate, etc.) not only tells the geological story of the rocks it has permeated but, crucially, determines the specific therapeutic potential of the spring for health and skin conditions.

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Thermal waters also contain dissolved gases like carbon dioxide and hydrogen sulfide, which enhance their biological, dermatological, and anti-inflammatory effects.

Key parameters such as pH and redox potential (Eh) define the water’s chemical balance and its ability to sustain life.In these extreme environments live extremophile microorganisms, capable of surviving at high temperatures and mineral concentrations.

Their biochemical activity contributes to mineral precipitation and rock alteration, revealing deep biogeochemical connections.

Beyond scientific interest, thermal waters have important practical applications.

In balneotherapy and dermatology, they are used to treat skin, respiratory, and musculoskeletal conditions.

From an industrial viewpoint, they represent a sustainable source of geothermal energy, used for heating, agriculture, and electricity generation.

In final analysis, thermal waters ascend to the surface as more than just heated hydration. They are a tangible memoir of the Earth’s inner workings—a perfect, dynamic testament to the harmony between geology, chemistry, and life. From the quiet workings of extremophile microorganisms to the complex mineral ratios that heal and rejuvenate, this ancient resource delivers profound, multifaceted value. It stands as a vital asset for the modern era: not only a source of tangible well-being in balneotherapy and dermatology, but also a frontier for scientific research and a promising avenue for sustainable geothermal development. They offer us a profound, enduring connection to the planet’s living, vibrant heart.

Dott. Renata Sanzi

Pharmacist and Medical Communication Specialist with over 15 years of experience in the pharmaceutical, cosmetic, and medical communication sectors. Expert in Medical Writing, Healthcare Training, and Scientific Communication Strategy for international agencies and companies. Combines solid scientific expertise with a clear and engaging communication style, promoting health education, prevention, and thermal wellness.


Areas of expertise: Balneology and Hydrotherapy, Aesthetic Medicine, Cosmetology, Rheumatology, Gastroenterology, Infectious Diseases.


Education


Degree in Pharmacy, University of Rome “La Sapienza”


Degree in Cosmetic Chemistry and Technology, University of Milan “La Statale”


Master in Healthcare and Pharma Marketing, “Il Sole 24 Ore” Business School, Milan


Master in Advanced Marketing and Business Communication, ISM Rome


Registered Pharmacist, Rome (No. 13630)



Selected Experience


Scientific direction and training in the pharmaceutical, cosmetic, and spa wellness sectors.

Medical Copywriter & Content Strategist for leading international agencies: McCann, Ogilvy, Dynamicom, TBWA, iCrossing.

Author of publications on natural springs and thermal heritage in Central Italy (Arkés Project, Esedra Publishing House).


Founder of SeReniti Natural Care, a natural biocosmetics brand.


Publications

Springs and Thermal Baths of the Sacco Valley – Arkés Project, Esedra Publishing House

Springs and Thermal Baths of the Lower Tiber Valley – Arkés Project, Esedra Publishing House


Personal Interests

Passionate about balneology, natural cosmetology, lyrical music, and aquatic sports.


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