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Water: The Substance You Thought You Knew

Posted by Mark L. Nelson, Ph.D. VP of Business and Science Development, CP Lab Chemicals on 28th Nov 2022

CAS Number [7732-18-5]                                            

One Molecule                 Many Molecules   

Formula H20 (18.02 amu)

Water is essential to all life, comprising between 70-90% of all organisms, and is the medium through which biochemical reactions take place. About 71% of the earth is covered by seawater, composed of 3.5% salts, mostly NaCl. Only 2% of water is freshwater, in the form of vapors, lakes and streams.

11 Quick Facts about Water

  • 1.All water came from extraterrestial sources- it is alien to the earth.
  • 2.It is the universal solvent, all matter eventually dissolves in it.
  • 3.It is the second most plentiful molecule in the universe- after hydrogen.
  • 4.It defies gravity, by capillary action, and feeds plants and outer brain regions by this mechanism.
  • 5.Hot water freezes faster than cold, called the Mpemba Effect after a Tanzanian student- know one knows why this happens.
  • 6.Is the only chemical that expands on freezing to form ice, which floats on water.
  • 7.It breaks the rules of chemistry, it should not exist as its made of light elements.
  • 8.All water has been recycled through animals, plants, rocks, and clouds.
  • 9.Water was one of the first elements agreed to exist by both Greek and Chinese philosophers.
  • 10.Water absorbs light strongly in the infra-red region of the light spectrum.
  • 11.Pure water can conduct electricity because it can form small concentrations of H3O+ and OH- ions.

Pure water does not occur in nature, and rainwater dissolves gases and traps particulates, dusts and smoke, including PM10, inhalable particles with diameters 10 micrometers and smaller, and PM2.5, fine particles smaller than 2.5 micrometers. As water dissolves substances it becomes acidic slowly by gaseous CO2 from soil microbes, dissolving rocks such as calcium and magnesium carbonates, increasing hardness (leading to hard water and soap scum), and affects alkalinity and salinity.

Water treatment with ferric sulfate or alum removes such impurities and problems, and municipal drinking water relies on such treatment routinely. Drinking water supplies for urban cities are treated with 15% sodium hypochlorite to kill pathogens, viruses and remedy tastes and odors, salt concentrations, turbidity and hardness.


Water for some industrial and boiler uses requires the use of distilled or highly demineralized water to remove dissolved salts, extending their uses in medicines and in industrial processes. Most of the processes and chemistry of water, however, were studied at 25 oC (room temperature) and little is known about processes from 0oC to boiling at 100oC.

Linus Pauling calculated that a molecule of water occupies 32.3 Angstroms, the crystal structure of which is held together by hydrogen bonds (H) with a bond energy of 5 kcal/mole. The tensile strength of ice, determined in 1885, is 142-223 psi (pounds per square inch), confirming the strength of the hydrogen bond, and the fact that the H-bond strength is itself variable.

The mass density of pure water at 1 atmosphere is 1.0 grams/milliliter at 4 oC, dropping to 0.958 grams/milliter at 100 oC, due to thermal expansion at this temperature.

Origins of Water on the Planet

Water was formed from the primordial earth gases cooling, when the earth cooled below 100 oC 3.8 billion years ago, and from meteor collisions delivering water, gases, and minerals.

Primitive algae related to cyanobacteria evolved energy harvesting methods splitting water molecules through photosynthesis and crude molecular pathways to generate oxygen. Microbiologist Lynn Margulis (at Harvard) postulated that the toxic oxygen produced 2.0 billion years ago initiated extinction of some bacterial species, but others adapted and flourished as protozoa, which were the first animals 800 million years ago. The algae produced an initial concentration of 5% oxygen, which has now leveled off to approximately 20% oxygen in our atmosphere today.

Drinking water is subject to federal Environmental Protection Agency regulations, can be used in extractions and the production of drug substances, but not in the preparation of dosage forms, reagents or test solutions.

Purified water is produced by distillation, ion-exchange methods, reverse osmosis, and other methods, removing dissolved solids, although some methods are not effective for removing volatile compounds or weak electrolytes. The Food and Drug Administration specifies regulations for all water used in medicine and commerce, and has identified eight types of water as a series of monographs detailing their compositions and safety requirements.


  1. Non-potable
  2. Potable (drinkable) water
  3. USP purified water
  4. USP water for injection (WFI)
  5. USP sterile water for injection                                                                                                                             
  6. LUSP sterile water for inhalation
  7. USP bacteriostatic water for injection
  8. USP sterile water for irrigation




At CP Lab Chemicals we provide water at all the different all the different grades used in medicine, research, commerce and industry, and can help you navigate the types needed for your work at Ask A Chemist

Water is also described by Types I through IV, whereType I is the most pure and descending in purity according to the table below, and as letters described as Types A through C, possessing limited numbers of heterotrophic bacteria and less than 0.03 endotoxin units (EU) per milliter for Type A, less for Type B, and not measured in Type C.

Choosing the right grade for the right application will save you time, money, and technical headaches and problems- Guaranteed.

Types of Water Available at CP Lab Chemicals

Cell and Molecular Ultra-Pure Water                                       Sterile Molecular Biology Grade USP
De-ionized Distilled Water                                                        Synthetic Fresh Water
Distilled Water                                                                           Water ACS Reagent
Lime Water                                                                                Water for Injection (WFI)
Standard Water (Fresh Water Substitute)                                 Water HPLC Plus
Sterile Purified Water                                                                Water LC-MS
Sterile Water for Injection                                                          Sterile Water
Sterile Water for Irrigation                                                          Ultra-Pure Water (electronics grade)

Ultra-pure water, also called Type I grade water (UPW), is used in the semiconductor, pharmaceutical, research and medical fields and have strict requirements for contaminants, metals, particles, and bacteria that could affect its performance. In pure water systems contaminants can enter during any step of the process, where carbon dioxide, salts, bacteria, metals, and leachable materials from tubing can affect the UPW. Other contaminants include sodium, oxygen, silica, particles, and organic residues. Metals are typically detected by ICP-MS (inductively coupled plasma mass spectroscopy) where methods allow for the routine determination of metals in parts-per-trillion (ppt). Bacterial analysis is conducted using ASTM method F1094, where bacteria recovered are counted on filters and grown at 28oC, for 48 to 72 hours, detecting both aerobes and facultative anaerobic bacteria.

We have all the water you need, and in the right grade for your application.

CP Lab Chemicals- All in One Place! 


Federal Food, Drug, and Cosmetic Act (FFDCA) (21 U.S.C. §§ 301 et seq).

FDA Current Good Manufacturing Practice regulations, Federal Register, Vol.43, No. 190 - Sept. 29, 1978, I. General Comments and Subpart C, para. 211.48

Federal Food, Drug, and Cosmetic Act (FFDCA) (21 U.S.C. §§ 301 et seq.)