-Arunava Nath, Syed Afsar Ali
Context: Water is not only precious for human life but also is vital to all lives on the planet. It plays many important roles in our body. It shows some unusual properties. Inclusion of molecules or ions in aqueous solutions may modify both the local structure and dynamic properties of water. Uses of water may vary from daily household chores, industrial purpose pharmaceutical applications, as a vehicle in homoeopathic pharmacy, therapeutic adventure, religious ablution in various faiths and others.
Aim: To perceive the different classification, variable properties and varied uses of water in daily life and its physiological importance.
Material and Methods: Literature review done from texts and journal articles to get a glimpse of the properties of water used for pharmaceutical and social purposes.
Results: Exploratory findings on physical, chemical, physiological and dynamic properties of water.
Conclusion: This paper attempts an approach in delving the subtle nuances of water with the basic purpose in creating curiosity among both the professionals and laity to come up with some refined ideas to work on this topic on a scientific platform.
Keywords: systematic naming, types of water, dynamic properties, homoeopathic pharmacy
Key messages: In Homoeopathy knowledge of usage of water is important not only from a pharmaceutical point of view but also the biophysics involved in carrying out the therapeutic virtues of the medicines. Collaborative participation involving interdisciplinary research is much needed to further the cause of Homoeopathy.
Abbreviations: IUPAC: International Union of Pure and Applied Chemistry; D: Self Diffusion Coefficient; HB: Hydrogen Bonding; cH: Centesimal Scale; API: Active Pharmaceuticals Ingredients; WFI: Water For Injection; FTIR: Fourier Transform Infrared Spectroscopy.
Definition: Water is a colourless, transparent, odourless, liquid which forms the seas, lakes, rivers, and rain and is the basis of the fluids of living organisms. 
Systematic naming: The accepted IUPAC name of water is “water”. The simplest and best systematic name of water is hydrogen oxide. 
Occurrence: Water covers 71% of the Earth’s surface. It is vital for all known forms of life. On Earth, 96.5% of the planet’s crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers, 0.001% in the air as vapour, clouds (formed of ice and liquid water suspended in air), and precipitation. A greater quantity of water is found in the earth’s interior. 
Historical Background: The ancient philosophers regarded water as a basic element typifying all liquid substances. Scientists did not disregard this view until the latter half of the 18th century. French chemist Antoine Laurent Lavoisier proved that water was not an element but a compound of oxygen and hydrogen. In a scientific paper presented in 1804, the French chemist Joseph Louis Gay-Lussac and German naturalist Alexander von Humboldt demonstrated jointly that water consisted of two volumes of hydrogen to one of oxygen, as expressed by the present-day formula H2O. 
Forms of water: In nature, water exists in three states: solid, liquid or gas.
Solid: Glaciers, icebergs, snow, hail, frost and ice crystals in the clouds are solid forms of water.
Liquid: Rain, dew and clouds are water droplets or liquid forms of water. Liquid water also covers three-quarters of the surface of Earth in the form of lakes, rivers and oceans.
Gaseous: Water vapour, fog, steam, and clouds are gaseous forms of water. 
The following features of water are being described under classification, properties, uses and physiological importance.
Classification of water
Mineral Water: Criteria
From deep subterranean reservoirs
From pure verified sources
Has nutritional properties
Naturally contains minerals
Bottled at the source
Internationally regulated 
Types of mineral water:
Chalybeate waters contain iron as ferrous bicarbonate and are good tonics.
Hepatic waters contain hydrogen sulphide and alkali sulphides and cure skin diseases.
Important sulphur springs in Northern India are at Jwalamukhi (Kangra), Tatta pani (Simla), Sohna (Gurgaon).
Bitter waters contain various salts, e.g. sodium sulphate, magnesium sulphate and are good laxatives.
Alkaline waters contain sodium bicarbonate and sometimes lithium bicarbonate which is beneficial for gout. 
Spring Water: Criteria
From subterranean water resources
Sources do not have to be verified pure
Does not have to contain a constant amount of minerals
Can be bottled from multiple sources
Limited official regulations
Tap Water: Criteria
Mostly derived from ground and/or surface water (lakes, dams, bank filtrates)
Usually processed before it is suitable for consumption
Multiple treatment procedures and chemical ingredients are allowed during
Table Water: Criteria
Combination of water from different sources (for example tap water) and can have
other ingredients added, for example, sodium.
Physically and chemically purified
Can be produced and bottled everywhere
May also be served using a tap system
Limited official regulations 
Bottled water: Types
This includes spring water, artesian water, mineral water, and purified water.
Spring water is groundwater. It comes from a water-bearing subsurface geologic formation known as an aquifer from which water flows naturally to the earth’s surface. The water of this type can be collected only at the spring or from a well that taps the aquifer that feeds the spring.
Artesian water is derived from a well in an aquifer that is under pressure due to overlying confining layers. Artesian or confined well water can be collected with external pumps that supplement the natural underground pressure. The word ‘‘artesian’’ was derived from the first deep wells that were drilled into confined aquifers in the province of Artois in northern France from about 1750.
Mineral water naturally contains at least 250 ppm of mineral salts such as calcium, chloride, sulfate, carbonate, and bicarbonate. No minerals can be added artificially, and it cannot come from a municipal source.
Purified (or demineralized) water may come from a municipal source and is treated by
one or more of the following water treatment processes:
Distillation: heating of water to produce water vapour which is then condensed and collected;
- b) Reverse osmosis, where water is filtered by passing it through a membrane;
- c) Deionization: a process where minerals are drawn to particles of the opposite electrical charge and then removed.
Sparkling water may include any type of naturally carbonated water. In addition, if the water
is treated, CO2 can be added to the product as long as the water has the same amount of CO2 as it had when it emerged from its source. Beverages that contain certain ingredients or additives, such as sugar, fall into a separate category called soft drinks. Thus, tonic water,
soda water, and seltzer are not considered bottled waters and are regulated differently. 
Properties of water:
It is a clear, colourless, tasteless and odourless liquid.
It is neutral and pH does not vary more than 6 to 7.
Specific gravity at 25oC: 1.000
Freezing point: 0oC
Boiling point: 100oC
Ionic product at 25 oC: 1 x 10-14
Latent heat of fusion at m.p: 79.72 cal/g
Latent heat of vapourisation at b.p: 539.4 cal/g
Heat of formation at 25 oC: 68.32 K.cal/mol
Critical temperature: 374.2oC
Surface tension at 25 oC: 71.97 dynes/cm
Viscosity at 25 oC: 8.937 millipoises
Refractive index nD20: 1.33300
It is practically a non-conductor of electricity due to its negligible ionisation into hydrogen and hydroxyl ions. It is also a bad conductor of heat.
It is a good ionising solvent for acids, bases and salts. It is an amphiprotic solvent i.e. capable of acting as an acid or a base. 
Purified water used in pharmaceutical manufacturing should pass this specification:
Clear, colourless, odourless and tasteless liquid.
pH between 5.0 to 7.0
Conductivity not more than 1 µS/cm.
Heavy metals not more than 0.1 ppm.
Residue on evaporation not more than 0.001%
Total bacterial count not more than 100 cfu/ml
total fungal count not more than 10 cfu/ml
Escherichia coli, Salmonella, Pseudomonas aeruginosa to be absent. 
Stability: It is very stable and does not decompose easily. Decomposition of water is not more than 2% even when heated at a high temperature as 2000 oC.
Reactions with metals: Metals form respective metal hydroxide and hydrogen gas when reacting with water. Metal + Water ⇨ Metal hydroxide + Hydrogen; Na (sodium) + H2O ⇨ NaOH (sodium hydroxide) + H2
Reactions with metallic oxides: water combines with metallic oxides to form bases.
e.g. CaO (calcium oxide) + H2O ⇨ Ca(OH)2 (calcium hydroxide)
Reactions with oxides of non-metals: with metallic oxides water combines to form acids. e.g. SO3 (sulphur trioxide) + H2O ⇨ H2SO4 (sulphuric acid)
The water of hydration: It readily forms crystalline hydrates with many compounds, e.g.
CuSO4.5H2O (Blue vitriol); Na2SO4.10H2O (Glauber’s salt).
Water as a catalyst: Water acts as an effective catalyst in many reactions. Perfectly dry gases invariably fail to react and trace of moisture is enough to promote chemical changes. e.g. rusting of iron, moisture favours the formation of rust which is hydrated iron(III) oxides Fe2O3. nH2O; n= water of crystallisation
Hard and soft water: A sample of water containing soluble salts of calcium, magnesium, or iron is called ‘hard water’ and it is difficult to get a lather when soap is added to such a sample of water. On the other hand, the sample of water is termed ‘soft water’ when it lathers readily with soap.  Several epidemiological investigations have demonstrated the relation between risk for cardiovascular disease, growth retardation, reproductive failure, and other health problems and hardness of drinking water or its content of magnesium and calcium. 
Maximum density at 4oC: Water molecules are united through hydrogen bonds to give giant molecules of the composition (H2O)x where x is a very large number. Water molecules in ice are held in a relatively open crystal structure by hydrogen bonds resulting in low density. On melting the ice structure collapses and molecules become closely packed causing an increase of density.  An interesting consequence of this peculiar feature of water is that the temperature of water at the bottom of a lake in the winter is almost always 4oC since the densest water will settle to the bottom, if it gets any colder or warmer, it will rise. Ice floats on top of lakes, preventing evaporation (and convection in the frozen layer), and lakes stay liquid underneath, allowing fish and other life to survive. 
High molar concentration: Provides an inexhaustible supply of H+.
Large dielectric constant: Allows ionic substances to dissolve producing charged species.
Very small dissociation constant: Produces extremely small but biologically significant [H+]. These are very reactive and have biologic importance out of all proportion to their minute concentration. 
High surface tension: This property is important for life. Water drops are stable and can be carried high up through stems due to the strong adhesive and cohesive properties.
Quantum Nature of the Hydrogen Bonds: It is known that hydrogen bonds are complex and because of the small mass of the proton it is often not appropriate to treat the proton in H-bonded system as a classical particle. The small mass of hydrogen atoms means that they are quantum mechanical in nature. Therefore the quantum nature of protons must be taken into account and issues such as zero-point motion, quantum delocalization, and quantum tunnelling are relevant. The relevance of quantum nuclear effects to liquid water has been demonstrated. In particular, from the first principle simulations and neutron Compton scattering measurements, the impact of quantum nuclear effects on the proton’s real space delocalization and water vibrational modes has been established. Upon increasing of H-bonds strength, the proton becomes more delocalized and consequently, the OH stretching frequency decreases. 
Dynamics of liquid water: The dynamic properties of water are unusual. In ordinary liquids, viscosity increases with pressure, while the self-diffusion coefficient D diminishes. In water at temperatures below 30°C and pressures below 2 kbar, a reverse tendency is observed. Extensive investigations of water dynamics by the nuclear magnetic resonance of different nuclei were fulfilled by Lüdemann and co-workers within wide ranges of temperature and pressure. The lower the temperature, the higher the nonmonotonous character of the D dependence on pressure. In Lüdemann’s works, investigations are extended to the temperature of 240 K and pressure 4 kbar. 
Dynamic properties of water/alcohol mixtures: Both intra- and intermolecular vibrational dynamics of water are expected to be modified significantly near a heterogeneous surface. Nibbering and Elsaesser extensively reviewed the experimental and theoretical investigations and discussed the potential of non-linear vibrational spectroscopy for the microscopic understanding of hydrogen-bond (HB) dynamics in the liquid state.  Homoeopathic potencies 12cH and above cross the Avogadro number, and as such does not contain any original drug molecules in their aqueous ethanol medium. It is thought H-bonded water structures preserved by ethanol carry the information of initial drug molecules. Potentized drugs show some differences with respect to their infrared (IR) absorption spectra. Infrared absorption measures the vibrational frequency of bonds. IR absorption measurements of aqueous ethanol show that ethanol molecules are monomolecularly dispersed and surrounded by water molecules at low alcohol concentration. At higher concentrations, water molecules are too few to accommodate all ethanol molecules in the clathrate-like structure.  Water ethanol mixtures form heterogenous micellar microaggregates as evidenced by other studies like sound absorption, X-ray scattering and light scattering. [18, 19] One theory explaining the physical basis of a homoeopathic potency states that hydrogen-bonded water structures preserved by ethanol molecules constitute the physical basis of a potency. [20, 21] These water structures vary in different potencies of a drug, and also in different potentized drugs. There is experimental evidence to show that water carries the information of a homoeopathic potency. [22-4] Potentized drugs also have a greater number of free water molecules. Different potentized drugs have a different amount of free water molecules and consequently different level of bound water molecules. The alcoholic O-H bond strength also varies in different drugs. This may be due to the difference in the H-bonded network in different drugs and also their bond strength induced by successive dilution and succussion during the preparation of homoeopathic potencies. 
Household chores: Humans, plants, and animals are made up of mostly water. We use water for drinking, washing, cleaning, bathing and cooking.
Outdoor activities: Much of our fresh water is also used outdoors for watering lawns, flower beds, and vegetable gardens, as well as washing cars and filling swimming pools. Cities use water for fire-fighting, street cleaning, and watering public areas such as parks, grass, trees, shrubs, and flowers. Water is also used to fill public drinking fountains, including those at schools and libraries.
Business field: Water is hugely used by restaurants, hospitals, laundries, dry cleaners, golf courses, hotels, car washes, beauty shops, barber shops, gas stations, and health clubs as well as all of the other businesses in town.
Agriculture and farmhouses: The amount of water needed on a dairy farm is a huge amount. Chickens, pigs, sheep, and all the other animals in a farmyard need drinking water to stay alive. Food must be grown for them to eat, and water is also required in the cooling systems used to keep production meat fresh. Vegetable and grain crops also require water. Water is used in spreading fertilizers, herbicides, and pesticides, which produce greater crop yield. Most of the water used on farms is used for irrigation.
Hydroelectric plants: Water is hugely used in hydroelectric plants. Hydroelectric plants capture the kinetic energy of falling water to make electricity. Of all the electricity in the world, about 20% is generated by hydropower. Hydropower generating prevents a lot of pollution.
In industries: Water is also essential in the industry. It is heated and the steam is used to run machinery. Water is used to cool hot metal such as in the production of steel. Water is also used to cool the air. It is an important element in many products like chemicals, drugs, lotions, shampoos, cosmetics, cleaners, and also beverages. Water is used in processing food and in innumerable factories and industrial processes including the manufacturing of paper.
Recreation purpose: Recreation is another way that we use and enjoy the water. Many people enjoy fishing, boating, sailing, canoeing, rafting, and swimming, as well as many other recreational activities that depend on water.
Transportation: This is yet another way where we use water. Many people use boats and ferries to commute to and from work every day. People also enjoy going on cruise ships or just going sailing. 
Pharmaceutical use: Water is a key ingredient used in many pharmaceutical and life sciences operations. Water is widely used as raw material, ingredient, and solvent in the processing, formulation, and manufacture of pharmaceutical products, active pharmaceutical ingredients (APIs) and intermediates. Water for injection (WFI) is used as an excipient in the production of parenteral and other preparations where product endotoxin content must be controlled and in other pharmaceutical applications, such as cleaning of certain equipment and parenteral product-contact components. 
Therapeutic applications: Hydrotherapy refers to the medicinal use of water, including hot tubs, cold water treatments, ice packs, vapours, saunas, mineral springs, hot springs, sitz baths, wet towel applications, water exercises, and water massage. Hydrotherapy increases blood circulation, including the circulation of the immune system’s white blood cells. Hydrotherapy also increases the body’s production of endogenous opioid peptides, particularly endorphins. Enhanced circulation and increased endorphins strengthen the immune system, reduce inflammation, heal injured tissue, improve well-being and energize the body. 
Homoeopathic pharmacy: Used for preparation of mother solutions of drug substances which are insoluble in alcohol but soluble in purified water. Dr Samuel Hahnemann classified them under OLD METHOD as Class V (A) and Class V (B) depending upon the solubility in the strength of 10% or 1% respectively. Drugs underclass V (A): Acids: Acetic acid, Nitric Acid; Inorganic compounds: Ammonium carbonicum, Causticum, Natrium muriaticum etc. Drugs underclass V (A): Oxalic acid, Phosphoric acid, Antimonium tartaricum etc. In preparing potencies, dispensing medicines, final cleaning of utensils or equipment. 
In different faiths: Water is considered a purifier in most religious faiths. Major faiths that incorporate ritual washing (ablution) include Hinduism, Christianity, Islam, Judaism, Sikhism, Shinto, Taoism, and Wicca. Immersion of a person in the water is a central sacrament of Christianity where it is called baptism. It is also a part of the practice of other religions, including Islam (Ghusl), Judaism (mikvah) and Sikhism (Amrit Sanskar). In addition, a ritual bath in pure water is performed for the dead in many religions including Islam and Judaism. In Islam, the five times daily prayers can be done in most cases after completing washing certain parts of the body called wudu using clean water. Water in Hinduism has a special place because it is believed to have spiritually cleansing powers. Water is an essential element in nearly all rites and ceremonies. 
Water has numerous roles in the human body. It acts as a building material; as a solvent, reaction medium and reactant; as a carrier for nutrients and waste products; in thermoregulation; and as a lubricant and shock absorber. The regulation of water balance is very precise, as a loss of 1% of body water is usually compensated within 24 h. Both water intake and water losses are controlled to reach water balance. Minute changes in plasma osmolarity are the main factors that trigger these homeostatic mechanisms. Healthy adults regulate water balance with precision, but young infants and elderly people are at greater risk of dehydration. Dehydration can affect consciousness and can induce speech incoherence, extremity weakness, hypotonia of ocular globes, orthostatic hypotension and tachycardia. The regulation of water balance is essential for the maintenance of health and life. On an average, a sedentary adult should drink 1.5 L of water per day, as water is the only liquid nutrient that is really essential for body hydration. 
Water is essential to humans and other life forms even though it provides no calories or organic nutrients. All the cell and organ functions that make up our entire anatomy and physiology depend on water for their functioning.  In Homoeopathy water plays a major role not only as a vehicle but in carrying over the essence of medicinal substances into the highest potencies through the unique method of potentization. Being homoeopathicians we need to focus more on the phsico-chemical-dynamic properties of water through interdisciplinary coordination for better understanding of the different facets of water and simultaneously the working principles of the modus operandi of homoeopathic medicines in the biological arena.
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The authors are grateful to institutional and departmental heads, library section staff of National Institute of Homoeopathy, Kolkata for their support. The authors are also thankful to Dr Anirban Patranabis, Physicist, Jadavpur University, Kolkata on elucidating on certain properties of water.