Common Methods Of Water Disinfection

Water disinfection is critical to ensure safe drinking water and avoid the spreading disease. By removing pathogens, contaminants, and other harmful microorganisms, water can be made safe for drinking and other uses. There are several methods for disinfecting water, depending on the source of the contamination.

Chemical processes include chlorine or other common disinfectants such as bromine, ozone, and chloramines. These chemicals react with organic materials and pathogens in the water to kill them. Physical processes such as filtration or ultraviolet (UV) light also remove or inactivate microorganisms. Biological processes use natural bacteria or enzymes to break down contaminants and make the water safer for drinking.

What Is Disinfection Of Water and how does it work?

Disinfection is a process used to kill or inactivate microorganisms such as bacteria, viruses, protozoa, and fungi. It is accomplished using chemical disinfectants or physical methods such as heat, ultraviolet (UV) radiation, or ozone.

These disinfection methods effectively kill most microorganisms but are not foolproof. Some pathogens may resist one or more of these treatments. For this reason, it is essential to use multiple methods when possible. Additionally, if improperly applied, disinfection can lead to the formation of harmful byproducts such as trihalomethanes.

Standard Methods of Water Disinfection

  • Chlorination: Chlorination is the most widely used method of disinfection. It involves adding chlorine, often sodium hypochlorite or calcium hypochlorite, to a water supply. Chlorine is effective against many microbial contaminants and can provide long-term protection against recontamination.
  • UV radiation: Ultraviolet radiation is the most effective disinfectant for water treatment. It can penetrate particles and microorganisms, thus destroying their cell structure and inactivating them. UV radiation produces no chemical compounds or byproducts, making it a safe and effective way to purify water.
UV radiation
UV radiation
  • Ozonation: Ozonation is a popular water disinfection method due to its effectiveness, convenience, and ability to reduce some chemical contaminants. Ozonation uses ozone gas, which contains three oxygen atoms, to oxidize the pathogenic microorganisms in water. This oxidation process kills the organisms and makes them unable to reproduce or infect other organisms. It also breaks down pesticides, herbicides, organic chemicals, and heavy metals that can be present in drinking water. The treated water is then filtered through activated carbon filters to remove any remaining ozone gas before it reaches consumers.
  • Pasteurization: Pasteurization is a process that uses heat to destroy harmful bacteria and microorganisms in the water while preserving its taste, smell, and appearance. The most common form of pasteurization involves heating the water to a temperature of 70-80°C (158-176°F) for at least 30 minutes. This method works well for killing off any potentially dangerous pathogens or contaminants in the water, but it does not make water safe to drink if chemical pollutants are present.
  • Distillation: A distillation process involves heating water to boiling so that the steam can be collected and condensed back into liquid form. This disinfection method is typically used for saline or brackish water, such as seawater, due to its ability to remove high levels of contaminants and salt. The downside is that it requires significant energy input and often results in a significant loss of water volume.
  • Silver treatment: Silver can disinfect water through a filter containing silver ions. It’s often found in the filters of drinking water systems and has been used for thousands of years. The silver kills off bacteria, viruses, and other pathogenic contaminants in the water. 
  • Chloramination: Chloramination is a mix of chlorine and ammonia that disinfects water. This method reduces the byproducts formed when disinfecting with straight chlorine and provides residual protection from bacterial contaminants. It typically works best at temperatures between 60 and 75 degrees Fahrenheit (15 to 24 degrees Celsius). Chloramination is used mainly in larger municipal water systems.
  • Chlorine dioxide: Chlorine dioxide is a chemical disinfectant commonly used in water treatment. It has the benefit of being more stable than chlorine and thus provides longer-lasting protection against pathogens. However, it can be corrosive to metallic pipes and may leave unpleasant tastes or odors if not properly managed.

Significant Factors Affecting Water Disinfection

  • Type of disinfectant:  The type of disinfectant used is an essential factor to consider when disinfecting water. Chlorine and ultraviolet light are two commonly used disinfectants, each with advantages and disadvantages. For example, chlorine kills many pathogens, but it can take several hours for the chemical to be completely effective. Ultraviolet light is fast acting and does not produce any byproducts, but it may not be as effective against certain types of bacteria.
  • Type and number of microorganisms: The method of water disinfection chosen will depend mainly on the type and number of microorganisms present in the source water. A more significant number or concentration of organisms requiring a higher level of disinfection will require more advanced methods than a smaller, less concentrated population. For example, if coliform bacteria are present in high concentrations, chlorination may be required for effective treatment.
  • pH and temperature: pH and temperature can affect the effectiveness of water disinfection. Increasing the pH of water, that is, making it more alkaline, can increase the effectiveness of chlorine-based disinfectants. Similarly, raising the water’s temperature helps speed up the rate at which reactions occur during disinfection processes. This can be particularly effective for UV light or heat-based treatments.
  • Contact time and disinfectant concentration: Two important considerations for water disinfection are contact time and disinfectant concentration. Increasing the contact time of water with a disinfectant will lead to better results. Long exposure increases the likelihood that all bacteria and viruses in the water will be killed. Similarly, increasing disinfectant concentration in the water can help improve effectiveness if done within safe limits – too much could harm aquatic life or cause health problems if ingested.
  • Physical and chemical interference: Physical interference methods involve either distillation or filtration. Distillation involves evaporating the water and then condensing it back into a liquid form, which is safer than its original state as some contaminants are left behind in the evaporated state. Filtration is used to strain out particulate matter from water, such as bacteria and viruses.

Importance Of Water Disinfection

  • Reduce the risk of water born diseases: Water disinfection is essential to reduce the risk of waterborne diseases, such as cholera and typhoid. Disinfecting water kills or inactivates harmful microorganisms, such as parasites, bacteria, viruses, and fungi. This makes it safe for drinking and other uses.
Water born diseases
Reduce the risk of water born diseases
  • Reduce the risk of medical conditions: To reduce the risk of contracting a medical condition, water disinfection methods must be used to kill off harmful bacteria and viruses.
  • Develop a healthy immune system: Water disinfection is essential to protect human health. It helps build robust immune systems and reduce the risk of waterborne illnesses caused by bacteria, viruses, parasites, or other contaminants. When drinking water is contaminated with these microorganisms, they can cause gastrointestinal distress, including vomiting and diarrhea. In extreme cases, it can even lead to death. People can ensure their drinking water is safe by using a reliable disinfection process and maintaining water safety standards.
  • Best for skin allergies: Ultraviolet (UV) light is a very effective water disinfection method. It is particularly beneficial for people who suffer from skin allergies and other sensitivities, as it does not require harsh chemicals that may adversely affect their skin. Unlike chemical treatment techniques such as chlorination or ozonation, UV light does not leave any residual chemicals in the water, which could later be absorbed through the skin.
    Best for skin allergies
    skin allergies
  • Necessary for pregnant women: Pregnant women should take extra precautions when dealing with contaminated water, as it could have adverse health effects. One way to reduce the exposure risk is to use water disinfection methods, such as boiling, chlorination, and filtration.
  • Better taste and odor: Chlorine, ozone, and ultraviolet light can improve water’s taste and odor. Chlorine is a widely used method for disinfecting municipal water supplies. Ozone may be added to the water supply to reduce the amount of chlorine needed for effective disinfection. Ultraviolet light can also be used to disinfect water, though it only provides effective disinfection when all particles and microorganisms within the water are exposed to UV light.
    Better taste and odor
    Better taste and odor

Water Disinfection When Camping

When camping, water disinfection is crucial in ensuring your drinking and cooking water is safe to consume. The most common methods for disinfecting water when camping includes boiling, chlorine dioxide tablets, iodine tablets, and ultraviolet light.

  • Boiling is one of the simplest and most effective ways to disinfect water while camping. Boiled water should be brought to a rolling boil for one minute (or three minutes at higher altitudes) to effectively kill harmful bacteria and viruses.


  • Chlorine dioxide tablets are another easy way to disinfect water while camping, as they require no boiling or special equipment. You need to drop a tablet into the water, wait for the specified amount of time as stated on the package, and then it is safe to drink.
  • Iodine tablets are cheaper than chlorine dioxide tablets and come in liquid and tablet forms. They should be used according to the instructions on their packaging and have a slightly longer wait time than chlorine dioxide tablets.


Can I use bleach to disinfect water?

No, bleach should never be used to disinfect water. Bleach contains toxic compounds and has been known to leave an unpleasant taste in the water that is difficult to remove.

What if the water is cloudy or murky?

In this case, filter the water before disinfection. Use a sedimentation process to settle out solid particulates, followed by filtration through screens or membranes. Alternatively, use adsorption processes such as activated carbon to remove particles and dissolved organic matter from the water.

Can I use iodine to disinfect water?

Yes, iodine is an effective water disinfection method. Using the correct dosage and contact time can be a reliable way of killing bacteria and other microorganisms in water. Iodine has been widely used to treat water before drinking or cooking.

How is a PAC used in water treatment?

How is a PAC used in water treatment
Using PAC in water

A powdered activated carbon (PAC) is a standard water disinfection method. This method utilizes granular activated carbon to absorb toxins and impurities from the water that passes through it. It is combined with an ultraviolet light system for additional protection.

PAC is widely used for municipal water treatment and can also be used in home systems to provide clean, safe drinking water. This method of disinfection works by adsorbing the impurities from the water before it is discharged into the environment.

Which chemical is most used in the water treatment of plants?

Chlorine is the most commonly used chemical for water treatment in plants. This can be done through chlorination, which involves adding chlorine gas to water, or by adding a chemical compound known as calcium hypochlorite (also referred to as “chlorine powder”).


Water disinfection is an essential process that helps to reduce the risk of contamination and illness. Several water disinfection methods include boiling, filtration, chemical treatment, ultraviolet light exposure, and chlorination. No matter which method is chosen, it is essential to ensure proper steps are taken to ensure safe drinking water. This includes testing the water quality before and after treatment to ensure that it meets safety standards for human consumption. The proper water disinfection measures can help provide safe drinking water and promote public health.

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