Ultraviolet Light Water Sterilizer



Ultraviolet sterilization is considered to be one of the most effective water treatment methods for disinfection. UV sterilizers work quickly in targeting and stabilizing all biological impurities found in water. Additional chemicals are not needed, therefore saving costs, including containing no danger of overdosing.

Ultraviolet or UV water sterilizer are used in water purification and treatment to make water healthier and prolong the life of water that has been treated and processed. The word “sterile” is defined as being free from living germs or microorganisms. An Ultraviolet sterilizer extraordinarily cleans water and kills bacteria and microorganisms that can be able to infest water even after it has been treated.

UV is a type of energy found in the electro-magnetic spectrum, lying between x-rays and visible light. Although we cannot see Ultraviolet light or rays, we are exposed to them every time we step out into the sun. In fact, Ultraviolet light is responsible for causing sunburns.

UV Water Purification systems use special lamps that emit UV light of a particular wave-length that has the ability, based on their length, to disrupt the DNA of micro-organisms. As water passes through a UV water treatment system, living organisms in water are exposed to UV light which attacks the genetic code of the microorganism and rearranges the DNA /RNA, eliminating the micro- organism’s ability to function and reproduce. If a microorganism can no longer reproduce, it cannot replicate, therefore it cannot infect other organisms with which it has contact. This process of exposing water to Ultraviolet light is simple but effective, destroying 99.99% of harmful microorganisms without adding any chemicals to the water.

UV Products

How Does UV Sterilization Work?

Many water purification systems take advantage of a UV water sterilizer even after processing their water. This is a well-known practice. Companies like Puritech highly recommend UV sterilizers as a post-treatment when treating water. Throughout the year’s ultraviolet technology has become well established as a chosen method for effective and economical water disinfection. Ultraviolet water sterilization claims many advantages: All microorganisms are virtually susceptible to ultra-violet disinfection.

For every penny of operating cost, hundreds of gallons of water are purified. NO additional chemicals are added and there’s no danger of overdosing. Once the water leaves the purifier, it is ready for use with no further contact time required. It has simple and easy to install and maintain. Compact units need a small space to operate and store. Ultraviolet water sterilizers deliver ongoing disinfection without special attention or measurement. There are no detections of chlorine taste or corrosion problems.

UV Disinfection System is an extremely effective way to combat microbial contamination in water. However, microbes have to be exposed to UV-C light in the proper amount in order to effectively disinfect the water. UV Disinfection Systems are used in many different applications ranging from the purification of drinking water in individual homes to disinfecting water supply of entire townships to industrial wastewater treatment. UV treatment for water is recognized as a safer and more cost-effective way to disinfect water for industrial applications

Why Use UV In Water

Water Bottling Plants

When you are in the water bottling business, you will need to consider using a UV sterilizer to make sure that you kill all the bacteria that builds up in your storage tank. Every time you open your filling tap, the water goes through the UV system killing all microorganisms that can be harmful to your body.

Cooking Water

Who wants to cook with unsafe water? We recommend that you add a UV sterilizer to your domestic system to ensure that the water is bacterial-free and safe for consumers.

If I’m On City Water

  • Water main breaks and broken pipes are a major cause for boil water advisories.
  • There are over 850 water main breaks every day in South Africa, and boil water advisories often aren’t issued for 24-48 hours after the contamination has occurred.
  • Out of the homes that have a water filtration device, only 10% have a system that can effectively protect against bacteria.
  • An Ultraviolet water filter system will protect your family from harmful bacteria even during a boil water advisory.

If I’m On Well Water

  • Wells are susceptible to bacteria from many sources.
  • Improper well casing, casing corrosion, and poorly-installed well caps are common sources for well water contamination.
  • Water levels change and fluctuate over time exposing the well to new opportunities for bacteria growth.
  • Bacteria, including total coliform bacteria and E. coli, were found in one third of wells, according to the US Geological Survey.

The UV Advantages

  • Destroys 99.99% of microorganisms.
  • Once installed, annual service is usually all that is required
  • Chemical disinfection methods change the taste & odor of water but UV does not
  • Only lamp & sleeve replaced annually
  • No disinfection byproducts and no wasted water
  • Works night and day, 24/7, consistently keeping water safe
  • Water flows through the system with essentially no pressure loss and requires no separate holding tank
  • No handling of chemicals

Applications Of A UV Sterilizer

Domestic Use

Commercial Use

Industrial Use

Parts Of The UV System

1. Ultraviolet Power Supply Unit

This is the main control of the Ultraviolet system. Some systems have a very simple controller, and others have a more complicated system that includes alarms, lamp change timers, trouble indicator lights, and more. Although Ultraviolet units vary in complexity and size, all controllers do basically the same thing of controlling the electrical output of the lamp and powers the UV-C light needed for water purification.

2. Inlet for untreated water

3. UV System Housing

This part of the system contains the Ultraviolet sleeve and lamp, and also controls the flow of water through the system.

4. Outlet for treated (clean) water

5. UV Bulb

The lamp of a UV system produces UV-C, which is Ultraviolet light considered to be germicidal. However, different lamps perform different functions, so the type of lamp used will be contingent on the application and disinfection requirements.

6. UV Quartz Sleeve

The quartz sleeve is made of quartz glass and is there to protect the UV lamp which is powered by electricity from the flow of water. The UV lamp transmits light through the tube into the water. It is important to clean the sleeve (generally when the lamp is changed) as minerals and contaminants in the water can cloud the glass tube.

What Does UV Remove?

UV is a safe, chemical-free way to treat water. Best of all, UV is effective in destroying 99.99% of harmful microorganisms, including:
  • E. coli
  • Giardia
  • Viruses
  • Flu
  • Typhoid Fever
  • Dysentery
  • Polio
  • Cryptosporidium
  • Cholera
  • Infectious Hepatitis
  • Salmonella
  • Cysts
  • Salmonella
  • Meningitis
  • Coliform

How to Get the Best Results From Your UV System

An ultraviolet water disinfection system cannot remove sediment, hardness, iron, lead or chlorine. That’s why pre-filters are often installed before a UV system.


Sediment found in city and well water can be large enough to create shadows for bacteria to hide behind and thus, hinder the systems’ ability to effectively treat water. UV manufacturers highly recommend a re-sediment filter be installed before the UV system to ensure proper water treatment.

Hard Water

If you have hard water, it may be necessary to have a water softener installed before the UV system. Hard water can cause scale build-up on the UV lamp which decreases the efficiency of the ultraviolet process.

Industrial Applications of UV Disinfection System

Ultraviolet disinfection system is not simply a lamp inside a pipe. The UV Reactor must be designed to ensure that all microbes receive sufficient exposure to the UV light (dose). Based on the hydraulic properties of water; the reactor needs to be optimized to guide the flow in a manner so as to maximize residence time and boost turbulence. Well designed Industrial UV water disinfection systems are producing consistently exceptional results in the industrial applications

Other Applications of UV Disinfection System

    • Food and Beverage – UV disinfection system can help to achieve a High-quality of water as per specifications laid down by the FDA
    • Bio- Pharmaceutical – Water used in Pharmaceutical and healthcare products and for CIP (Cleaning in Place) must be free of chemicals like chlorine, ozone, and pathogens. Most pharmaceutical companies depend on UV systems for water disinfection.
    • Cosmetics – Water that is free of microorganisms and toxins ensures quality and enhances the shelf life of cosmetics. UV Sterilization is the preferred choice for the cosmetic industry across the globe.
    • Centralized Drinking Water – A UV drinking water disinfection system is an easy, affordable solution to ensure pure water in each and every tap of your home or office
    • Waste Water Disinfection and Reuse – To combat the problems of water scarcity and the rising cost of fresh water, UV Disinfection can help by treating the wastewater in the tertiary stage. UV systems that are specially designed for wastewater can thus disinfect wastewater so that the water can be reused for secondary purposes such as flushing and gardening.
    • Swimming Pools – Traditionally, chlorine has been in use to ensure clean water in swimming pools. However, it is increasingly being known that with chemical disinfection, chemical reacts with many other organic matters to form hundreds of new chemicals which are harmful. While UV is recognized as a safer and more cost-effective way to disinfect swimming pools.

Benefits of UV Disinfection System

Natural – UV is nature’s way of purification.

Environmentally Friendly – No Toxic by-products are formed during the UV disinfection process

Effective – All known microorganisms are susceptible to UV light

Economical – Lowest operating cost amongst disinfection systems

Safe and Chemical Free – No addition of chemicals hence no danger of overdosing

Fast – It is In-contact purification therefore Instant

Easy to Manage – Well designed systems like the Alfaa UV systems come with many advanced features like CFD (Computational Fluid Dynamics), high-efficiency electronic ballasts, and extremely precise UV intensity monitors which make them highly effective and hence easy to manage.

Does a UV  Disinfection System need periodic maintenance?

There can be some cases where the water is not adequately pre-treated and turbidity levels are low.  In such cases, routine inspection and cleaning can be carried out every 6 months. In the case of high turbidity and hardness, the cleaning frequency might need to be increased. Finally, the UV lamp has a limited life and must be replaced once it is exhausted. In the unlikely event of premature failure of the lamp, the monitoring circuit will provide the signal to advise replacement.

Does a UV  Disinfection System need periodic maintenance?

Principles of UV Disinfection – Home Water Treatment

UV radiation has three wavelength zones: UV-A, UV-B, and UV-C, and it is this last region, the shortwave UV-C, that has germicidal properties for disinfection.  A low-pressure mercury arc lamp resembling a fluorescent lamp produces the UV light in the range of 254 manometers (nm).   A nm is one billionth of a meter (10^-9 meter). These lamps contain elemental mercury and an inert gas, such as argon, in a UV-transmitting tube, usually quartz. Traditionally, most mercury arc UV lamps have been the so-called “low pressure” type, because they operate at relatively low partial pressure of mercury, low overall vapor pressure (about 2 mbar), low external temperature (50-100oC) and low power. These lamps emit nearly monochromatic UV radiation at a wavelength of 254 nm, which is in the optimum range for UV energy absorption by nucleic acids (about 240-280 nm).

In recent years medium pressure UV lamps that operate at much higher pressures, temperatures and power levels and emit a broad spectrum of higher UV energy between 200 and 320 nm have become commercially available. However, for UV disinfection of home drinking water at the household level, the low-pressure lamps and systems are entirely adequate and even preferred to medium pressure lamps and systems. This is because they operate at lower power, lower temperature, and lower cost while being highly effective in disinfecting more than enough water for daily household use. An essential requirement for UV disinfection with lamp systems is an available and reliable source of electricity. While the power requirements of low-pressure mercury UV lamp disinfection systems are modest, they are essential for lamp operation to disinfect water. Since most microorganisms are affected by radiation around 260 nm, UV radiation is in the appropriate range for germicidal activity. There are UV lamps that produce radiation in the range of 185 nm that are effective on microorganisms and will also reduce the total organic carbon (TOC) content of the water.  For typical UV system, approximately 95 percent of the radiation passes through a quartz glass sleeve and into the untreated water.  The water is flowing as a thin film over the lamp.  The glass sleeve is designed to keep the lamp at an ideal temperature of approximately 104 °F. 

UV Radiation (How it Works)
UV radiation affects microorganisms by altering the DNA in the cells and impeding reproduction. UV treatment does not remove organisms from the water, it merely inactivates them. The effectiveness of this process is related to exposure time and lamp intensity as well as general water quality parameters.  The exposure time is reported as “microwatt-seconds per square centimeter” (uwatt-sec/cm^2), and the U.S. Department of Health and Human Services has established a minimum exposure of 16,000 µwatt-sec/cm^2 for UV disinfection systems.  Most manufacturers provide a lamp intensity of 30,000-50,000µwatt-sec/cm^2.  In general, coliform bacteria, for example, are destroyed at 7,000 µwatt-sec/cm^2.  Since lamp intensity decreases over time with use, lamp replacement and proper pretreatment are key to the success of  UV disinfection. In addition, UV systems should be equipped with a warning device to alert the owner when lamp intensity falls below the germicidal range.   The following gives the irradiation time required to inactivate completely various microorganisms under 30,000 µwatt-sec/cm^2 dose of UV 254 nm

Used alone, UV radiation does not improve the taste, odor, or clarity of water. UV light is a very effective disinfectant, although the disinfection can only occur inside the unit. There is no residual disinfection in the water to inactivate bacteria that may survive or may be introduced after the water passes by the light source. The percentage of microorganisms destroyed depends on the intensity of the UV light,  the contact time, raw water quality, and proper maintenance of the equipment.  If material builds up on the glass sleeve or the particle load is high, the light intensity and the effectiveness of treatment are reduced.  At sufficiently high doses, all waterborne enteric pathogens are inactivated by UV radiation. The general order of microbial resistance (from least to most) and corresponding UV doses for extensive (>99.9%) inactivation are: vegetative bacteria and the protozoan parasites Cryptosporidium parvum and Giardia lamblia at low doses (1-10 mJ/cm2) and enteric viruses and bacterial spores at high doses (30-150 mJ/cm2). Most low-pressure mercury lamp UV disinfection systems can readily achieve UV radiation doses of 50-150 mJ/cm2 in high quality water, and therefore efficiently disinfect essentially all waterborne pathogens. However, dissolved organic matter, such as natural organic matter, certain inorganic solutes, such as iron, sulfites and nitrites, and suspended matter (particulates or turbidity) will absorb UV radiation or shield microbes from UV radiation, resulting in lower delivered UV doses and reduced microbial disinfection. Another concern about disinfecting microbes with lower doses of UV radiation is the ability of bacteria and other cellular microbes to repair UV-induced damage and restore infectivity, a phenomenon known as reactivation. 

UV inactivates microbes primarily by chemically altering nucleic acids. However, the UV-induced chemical lesions can be repaired by cellular enzymatic mechanisms, some of which are independent of light (dark repair) and others of which require visible light (photorepair or photoreactivation). Therefore, achieving optimum UV disinfection of water requires delivering a sufficient UV dose to induce greater levels of nucleic acid damage and thereby overcome or overwhelm DNA repair mechanisms.

Maintenance of a UV System

Since UV radiation must reach the bacteria to inactivate them, the housing for the light source must be kept clean. Commercial products are available for rinsing the unit to remove any film on the light source. An overnight cleaning with a solution of 0.15 percent sodium hydrosulfite or citric acid effectively removes such films. Some units have wipers to aid the cleaning process. 

UV systems are designed for continuous operation and should be shut down only if treatment is not needed for several days. A few minutes for lamp warm-up is needed before the system is used again following shut-down. In addition, the plumbing system of the house should be thoroughly flushed following a period of no use. Whenever the system is serviced, the entire plumbing system should be disinfected with a chemical such as chlorine prior to relying on the UV system for disinfection. 

UV lights gradually lose effectiveness with use, the lamp should be cleaned on a regular basis and replaced at least once a year. It is not uncommon for a new lamp to lose 20 percent of its intensity within the first 100 hours of operation, although that level is maintained for the next several thousand hours. As stated previously, units equipped with properly calibrated UV emission detectors alert the owner when the light intensity falls below a certain level. 

The treated water should be monitored for coliform and heterotrophic bacteria on a monthly basis for at least the first 6 months of the device’s use. If these organisms are present in the treated water, the lamp intensity should be checked, and the entire plumbing system should be disinfected with a chemical such as chlorine.

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