What is Sterile Water?

by Kate Onissiphorou

Sterile water is a type of purified water. It’s similar to distilled water, but with one key difference: it’s less pure because it contains inorganic substances. Sterile water has several applications in health and medicine, chemical manufacturing, and pharmaceutical manufacturing. 

In distilled water, both organic and inorganic substances have been removed from the water. Meanwhile, sterile water has had organic contaminants like bacteria removed, but still contains inorganic minerals and salts in trace amounts. The presence of inorganic substances in sterile water is responsible for its slightly acidic pH level, which ranges from 5.0 to just under 7.0. In comparison, distilled water has a neutral pH of 7.0.

Is sterile water the same as boiled water?

Sterile water isn’t the same as boiled water. Boiling is a simple method of ensuring that pathogens in water are killed. It is sometimes used when sterilising water, but only on a small scale. 

Boiling water will not necessarily remove impurities, whether they’re organic or inorganic. However, since most microorganisms cannot survive at the boiling point of water (100°C at 1 atm (101.325 kPa)), all the common pathogens are killed in the process of boiling.

Transparent electric kettle with boiling water on a table in a kitchen

There are other more effective methods of sterilising water, such as irradiation, ozonation, and chlorination. In large-scale water purification, such as treating our tap water, boiling is neither practical nor energy efficient.

During the process of sterilisation, water undergoes several stages of filtration to remove large organic molecules, including the remains of the microorganisms. However, some inorganic impurities, like salts and minerals, may still remain.

How do you make sterile water?

The simplest way of making sterile water is to boil it in a pressure cooker at 121°C for at least 20 minutes. Being sterile simply means that it’s free from any viable microorganisms that could potentially cause harm or infection.

Most bacteria and viruses become inactive at temperatures approaching the boiling point of water. You do not necessarily have to boil water to kill most pathogens. However, if you want to make sure, you must boil water for at least one minute. Lower temperatures may not inactivate some of the microorganisms

The high temperature of boiling water can kill microorganisms in several ways:

  • It can rupture the phospholipid bilayer of cells or the protein-lipid envelope of viruses
  • It can disrupt the normal biological functions of cells, such as metabolic pathways
  • It can denature proteins, leading to both structural and functional destructions that are irreversible. It’s much like boiling an egg, which cannot be undone

    Selective focus UV T.O.C reduction sterilization light for EDI system to industrial water treatment manufacturing
    Sterilising water on an industrial scale

Can you drink sterile water?

Commercially produced sterile water is not intended for drinking. It’s usually intended for washing wounds, and may contain some minerals. Dissolved air is also generally removed from water during sterilisation. Therefore, it may not contain normal amounts of dissolved oxygen, which is needed to contribute to the pleasant taste of drinking water.

Additionally, medical sterile water for irrigation should not be drunk because it’s hypotonic. This means that it can readily be absorbed by the cells of the body, and this can lead to various conditions, including:

  • Very low levels of sodium in the blood (hyponatremia)
  • Very low levels of proteins and other nutrients in the blood (hypoosmolality)
  • Fluid overload in the cells, caused by rapid absorption of water due to osmosis

These conditions are dangerous and may result in permanent morbidity or even death. Aside from medical irrigation, sterile water can also be injected or inhaled as nebulised particles of water mixed with some medicines. Some of the serious side effects of sterile water are the following:

  • Hives or urticaria: Patients may feel itching on their skin
  • Breathing difficulties: This usually happens if the water is used as a nebulised bronchodilator for asthma patients
  • Swelling: The face, lips, tongue, or throat may become swollen due to rapid and excessive cellular absorption of water

If you experience one or more of these symptoms, you will need immediate medical attention. Postoperative patients may be at risk of experiencing some of these side effects.

Common uses of sterile water

Sterile water is commonly used for medical purposes. It’s used for irrigating or cleaning wounds, and some medicines may be dissolved in sterile water either for intramuscular or intravenous injections. It’s also used in nebulisers to treat asthma attacks. 

Sterile water for injection

In injections, the proportion of medicine to water depends on several factors, such as the intended dosage, the body weight of the patient, and the type of medicine that will be administered. Sterile water for injection is contained in a single-use container that cannot be resealed. Any excess amount of water must be discarded. Vial with sterile water for injection

What is sterile water for injection?

Sterile water for injection is for parenteral use only, which means it should not be taken orally. Medicines can be dissolved in it, or it can be used to dilute medicines for specific dosages. The water can then be injected into a vein or in intermuscular spaces depending on the intended drug effect.

Adding medicine for dilution must be done in a completely aseptic manner to prevent contamination. For instance, a sterilised syringe may be used to add medicine into the sterile water container for dilution. It must not be administered without any solute because it may result in hemolysis, the destruction of blood cells that release haemoglobin from the red blood cells because of excessive fluid absorption by the cells.

Sterile water for wound irrigation

In medicine, irrigation means washing a wound or body cavity. It’s divided into three types:

  • Bladder irrigation: The sterile water for irrigation is used to prepare a solution to clean the bladder or to introduce medication via flowing water
  • Bowel irrigation: The sterile water for irrigation is pumped into the large intestine via the anus to clean the intestinal tract or introduce medicine
  • Wound irrigation: This can be done either as a first aid for minor wounds or as part of surgical procedures. Slightly pressurised water may be used to flush debris from an open wound Washing a wound on a person's hand with cotton wool and sterilised water

Home use of sterile water

You don’t necessarily need to buy sterile water. Depending on what you’re using it for at home, you may be able to prepare it yourself. For instance, if you only need to wash a wound, you can use boiled tap water.

However, for more sensitive treatments, such as treating sinus problems, you must use the sterile water product prescribed by your doctor.

Where to buy purified water

As a consumer, you can typically buy purified water from supermarkets, hardware stores, and petrol stations. 

If you’re a business wanting to buy pure water in bulk, you would normally purchase from a chemical manufacturer like ReAgent, or a water supplier. At ReAgent, we sell different types of pure water to business customers, including:


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