Common Water Disinfection Techniques

Water is the only nutrient that is indispensable for the continuation of life. Being without food for a certain period of time may not cause huge problems; however, there is no way that any dehydrated creature will survive. The quality of the water, which is so important and valuable for continuing life, is as important as its existence. Contaminated water sources are also a significant health threat to lives.

It is the treatment process that ensures that the water healthily reaches the consumer. The water treatment process is essential for making the water healthy. The stages of the general treatment processes applied are as follows.

Flocculation (or coagulation)



It can be summarized as disinfection.

Obtaining or treating water from clean sources to the end consumer is an issue that affects public health completely. In the past, it has been known that dirty waters can cause serious outbreaks, even in large societies.

The disinfection process, which is the last step of the water treatment process, is the most important step in obtaining clean water. The purpose of the process is to destroy microorganisms in drinking and drinking water. Disinfection is carried out in two ways:



The methods used in water disinfection are done in the following ways:

1. Boiling

2. Chlorination

3. Disinfection with ozone

4. Disinfection with ultraviolet

5. Disinfection with potassium Permanganate

6. Iodized disinfection

According to the World, chlorination, which is the most commonly used method for disinfection of water, is one of the most important developments in the field of public health and is the most reliable disinfection method among the alternatives currently available Health Organization.

It is important to choose the right method for the disinfection of water. In addition to using water, the structure and characteristics of the water and the network to which it will be distributed should be well known.

If network integrity is under full and continuous control:

– Disinfection of groundwater: primary bacterium effect

– Disinfection of superficial water sources: effective against bactericides + parasites and viruses, as well as colour and odour-relieving efficacy

If network integrity is not complete:

– First of all, disinfectants with high primary disinfection effectiveness and residual protective effectiveness should be selected

Disinfectant to be used for water disinfection;

• Ensure continuity, be easy to apply and give quick results

• Must be cheap

• No toxic effect

• The method should not have a physical and chemical pollutant effect

• It should be accepted by community members

• Should not disturb the characteristics of the waters such as colour and taste

• It must completely kill and destroy disease-causing factors.


It is the disinfection process in which the water is boiled for about 10 minutes. During this process, spore microorganisms do not die, but other microorganisms are destroyed. By boiling the water, the gases that are tasteful in the water are removed from the environment. Therefore, it is necessary to ventilate the water (captain rough discharge) to eliminate taste disorders in the water. Disinfection by boiling method is valid in home conditions. Although it is not a very safe disinfection method, it should be preferred in mandatory situations.


Chlorine is a substance with a high disinfectant effect. For chlorine to have a full effect on microorganisms in water, the chlorine dose and the duration of the chlorine in the water must be fully adjusted. The water regulation for human consumption has determined that the amount of chlorine that should be present in the water is no more than 0.5 mg/lt. In other words, it means that there are no more than 0.5 mg of free chlorine per litre of water.

The main chlorinated substances used are:

Peeled hypochlorite (NaOCl2)

Calcium hypochlorite (CaOCl2)

Javel Water

Chlorinated tablets

Lime cream (calcium hypochlorite)

Advantages of water disinfection with chlorine:

The known pathogen is effective on many microorganisms and destroys them or prevents them from reproducing.

It is the only method that provides continuous disinfection from the facility where the water is processed to the fountain where it reaches the user.

By-products are the most examined disinfectant.

Provides taste and smell control, oxidizes many natural organic substances that can cause bad smell and taste in drinking water.

Eliminates sulphides and odours that occur as a result of vegetation.

Controls biological growth,

Chlorine provides chemical control, breaks down hydrogen sulphide, ammonia and other nitrogenous compounds that can be found in water,

Contributes economically,

Apart from drinking water, it can also be used to disinfect water used for recreational purposes (such as pool, hot spring, etc.).

Things to consider about chlorination:

Free chlorine should remain in the water for at least 30 minutes (contact time.

The best stage for chlorination is the stage immediately before the storage or distribution process when the treatment processes are finished.

Chlorine should not be added to water before slow sand filters or other existing biological treatment stages. Solid forms of chlorine should not be thrown directly into the water to be disinfected but must first be mechanically mixed with a small amount of water.

Under normal conditions, the conventional chlorine level (free or active chlorine) should be a maximum of 0.5 ppm.

>1ppm chlorine level must be provided in extreme cases

First of all, treatment processes should be applied to reduce the turbidity of water.

Protection measures (watersheds, storage and distribution systems) should always take precedence to prevent waterborne infectious diseases.


It is carried out by contacting the ozone gas obtained from the specially designed Ozone generator with water. 1 – 1.5 grams of ozone are used for each cubic meter of water. In this disinfection process, results are obtained quickly. However, it is not preferred because it is an expensive disinfection method and does not have continuity (it should be effective up to the extreme, especially in mains waters). All microorganisms are destroyed except spores.



It is the primary method of disinfection. It does not provide residual disinfection. Rays with a wavelength of 0-3900 Angstrom are called Ultraviolet. Water disinfection uses rays with a wavelength of 2500 – 3000 Angstrom. For this, high voltage electric lamps are used. Disinfection is carried out by applying 30 sec to the water with a distance of 10 cm. It does not affect sports.



Oxygen occurs when it is thrown into the water. Oxygen kills microorganisms other than spores due to the oxidant effect in the water. 0.03 gr. is added to 1 litre of non-murky water, and twice this amount is added to the murky waters and left for 15 minutes. When you give the water violet colour, it needs to be removed. This happens with potassium hyposulfite. It is used for a small amount of water. It is more effective against cholera vibrio than others. It is not used much because it leaves black, brown sediment in the containers.



Iodine also has a high bactericidal effect. Although it is recommended for disinfection of water, it is not economical.1 litre of water is made with the calculation of 2 drops of tincture. Water should be clear in water disinfection with iodine, and the container used should be glass or enama. It is used for a small amount of water.


Monitoring disinfection:

Disinfection of water should be followed before and after the procedure. Microbiological analyses should be carried out by taking samples from the waters regularly, and changes should be made to the disinfection dose or procedures when necessary according to the results.

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