UV disinfection is a treatment technology used for the production of pure water! UV disinfection works by emitting radiation via a light wave and is particularly effective against micro-organisms and pathogens such as bacteria, viruses or protozoa. Learn more about the capital and operational costs, the functioning, the strengths and weaknesses and even the different uses of UV disinfection systems.

It should be noted that we are addressing the subject from an industrial point of view, but that the operation of a residential system is very similar. Also, the prices given in the article are estimates and can vary significantly depending on the different situations.


What is UV disinfection (irradiation)?

UV treatments are a type of disinfection which allow the deactivation of certain organisms that can be found in water. This disinfection is usually part of the water polishing step and cannot be used as a primary treatment as it would be ineffective against overly contaminated water.

This type of disinfection works on the principle of irradiation. The irradiation is done by using a mercury lamp which, via an electromagnetic transfer, sends energy that will attack the genetic material (DNA) of the organisms present in the water.

In other words, when activated, UV lamps emit waves of 185nm or 254nm in length that will attack the particles in the water. In comparison, UV waves are much shorter than infrared waves, which generally measure 780nm to 1mm.

To destroy contaminants, ultraviolet light is absorbed by the DNA bases of microorganisms and will cause changes in the chemical bonds. These changes interfere with DNA transcription and replication, thus disabling the cell's ability to multiply. UV radiation is therefore a measurable agent that directly damages DNA.

To operate, the UV lamp will emit its waves inside a box where the treated water will pass. The waves emitted are in the form of monochromatic lights that can change depending on the type of lamp used. The effectiveness of the UV treatment is intimately linked to the water parameters, the intensity of the lamps and the length of exposure. The water parameters affect the efficiency of the UV treatment since the presence of particles, or any other type of obstructions severely affect the emitted waves since they can be easily blocked. It is mainly for this reason that UV irradiation cannot be used as a primary treatment.

Uses of UV disinfection

Widely used in many sectors such as pharmaceutical, food and ultra pure water production, UV disinfection is very effective against bacteria, viruses, spores, cysts and all other types of microorganisms. UV can also be used to remove residual ozone after ozonation or in combination with ozone for advanced oxidation treatment.

On the other hand, it is useless to install a UV disinfection system alone if your water is heavily contaminated with organic compounds or suspended solids. A primary treatment would then be necessary before the UV polishing. In addition, it is important to remember that this type of disinfection will not affect the color of the water and that even though the micro-organisms will be deactivated by the UV irradiation, their bodies will remain in the water and create sediment. For the production of ultra pure water, these bodies must be removed by downstream filtration.

Strengths and Weaknesses of UV Disinfection

To begin with, UV disinfection systems have the advantage of being inexpensive to operate. The average lamp lasts 9 to 12 months and when it needs to be replaced, it costs about $100 to $200 each. Therefore, the cost of replacing the lamps varies according to the system owned and the number of lamps present inside the equipment. Then, the protective sleeve for the lamp must be changed every 12-24 months since it gets damaged with time and ends up affecting the efficiency of the UV waves. Like the UV lamps, the sleeves cost between 100 and 200$ each. In addition to these costs, one must take into account the energy demand for a continuous treatment.

  • The estimated costs are based on a system providing approximately 500 GPM of treatment and we have included the following costs in the estimate: energy, lamps, labor.
  • It is important to note that these are only estimates and that these costs can vary greatly depending on the system, demand and situation.

​In terms of the CAPEX of a UV system, again, the costs are relatively low. When purchasing a system, the factors to consider are generally the purchase of the reaction chamber, which is where the disinfectçakes place. Then, the electronic equipment that allows the lamps to light up: ballast, intensity sensor, controller, etc. And finally, the installation and activation costs.

Note that these estimates are approximate and that fluctuations may occur due to sporadic changes in prices.


As mentioned above, the UV treatment is continuous, which means that the disinfection never stops and that no decrease in production is perceived when there is a treatment. Moreover, contrary to what one may believe, UV irradiation is a physical process and not a chemical one. This means that no transportation, storage or handling of chemicals is required.

Although UV disinfection systems have many advantages, it is important to remember that they are not suitable for use as a primary treatment. In addition, there may be times when it is not effective or when standards require the use of some chemical. In these cases, UV irradiation can be used to remove the residues of the chemicals used upstream. Several factors can make that a UV disinfection is not sufficient, we can think of the photoreactivation which is a mechanism of repair of the DNA allowing certain contaminants like the prokaryotes or the eukaryotes to recover their capacity of reproduction.

Finally, it should be noted that handling UV lamps is a challenge as they cannot be stored for too long and should not be touched with bare hands. As mentioned above, UV waves are easily blocked by any contaminants. Touching the sleeve or the UV lamp will leave a fingerprint on it and affect the effectiveness of the irradiation.

A good solution, according to your needs

As you have seen, UV disinfection is an interesting option in many ways and has varying capabilities depending on its use. It is important to understand that this physical water treatment process is primarily used in the production of high-purity water. It is not a necessary treatment for all industrial applications.

On this note, we hope that we have answered your questions about this type of disinfection. If you would like to learn more about other types of disinfection used in the pharmaceutical industry, I invite you to visit this article: disinfection technique for a pharmaceutical water purification system.

In the meantime, if you have any questions or comments, we will be happy to answer them.