UV Treatment for Bacteria - How Does UV Kill Bacteria?

Bacteria is a major concern for many as we have all heard stories of people getting sick from drinking contaminated water and in some cases it has cost people their lives. Although the latter outcome is extremely rare, the fact is that bacterial contamination scares people. What options are there to protect oneself from bacteria in their drinking water? In recent years, Ultraviolet (UV) technology is winning the battle as the preferred technology to deal with this concern. But how does it work? Is it effective? Please note the following quoted material from Viqua, a leading innovator and manufacturer of UV Water treatment technologies.

"The ultraviolet (UV) treatment process is an extremely quick physical process. Ultraviolet light mutates and/or degrades DNA. DNA (or deoxyribonucleic acid) is the part of the cell that gives an organism its instructions on how to function and reproduce.

When the DNA is damaged, the organism becomes unable to function because its “instructions” are garbled or missing. An organism that has no instructions cannot function and reproduce, and cannot cause infection. It is rendered harmless and eventually dies.

In the UV disinfection process, water is purified as it runs through a stainless steel  chamber (also called a “reactor”) that contains a special UV- producing lamp. As the water  flows past the lamp, the microbes in the  water receive a lethal dose of UV.

The water is then safe to drink. However, different organisms require different levels of UV energy to disrupt their DNA. This energy level is known as a UV dose.

How Do You Calculate UV Dose?

UV Dose is expressed in mWs/cm2 or mJ/cm2. The accepted standard for most applications is 30 mJ/cm2. A slower flow rate will result in a higher UV dose. The longer the chamber and the longer the water stays in contact with the UV lamp, the higher the dose. Most UV manufacturers have a variety of systems suitable for different dose requirement

Intensity is the quantity of UV light per unit area, and time is the amount of “contact time:” the water spends in the chamber.

UV dose is determined by calculating two amounts: UV light intensity and time.

Depending on the type of microorganism you are dealing with, your system needs will be different. Consult a water treatment professional to ensure that you are getting the right kind of system for your needs.

Factors That Affect UV Dose

Different factors can affect UV dose and the ability of UV to deactivate organisms in the water. If there is turbidity (large amounts of particles) or water hardness, microorganisms can “hide” behind these particles. This hampers UVT, or UV transmittance, the amount of UV that actually penetrates the water. With a low UVT, “hidden” microorganisms will not receive the required dose of UV light to deactivate their DNA, and the water will not be properly disinfected.

Performing a water test will indicate what type of pre-treatment a UV system requires to increase UVT and produce maximum effective disinfection. The following chart shows the ideal state for maximum results:

ParameterInfluence / EffectLimits

 UV Transmittance Measure of absorption of UV light, UVT can affect system sizing requirements > 75% UVT @ 254nm

 Iron Can affect both UVT and sleeve fouling < 0.3 ppm (0.3 mg/L)

 Hardness Can cause sleeve fouling < 120 ppm (7 gpg)

 Turbidity Can shield pathogen, post UV contamination < 1 NTU

 Tannins Can affect UVT and system performance < 0.1 ppm (0.1 mg/L)


For NSF 55 Class A requirements (which may apply where you live, check with your local municipal health region), UV dose is required to be 40 mJ/cm2. If you aren’t sure if you are required to use an NSF-certified system for regulatory requirements in your area, ask your local water treatment professional.

They should be able to inform you about any laws or regulations that regulate water treatment equipment where you live."

For more information on UV technologies or to obtain a quote on a system designed for your application, please give us a call at 888 983 2688. We will be pleased to answer any questions you have.


Is Bottled Water the Best Option?

The office water cooler has become a staple appliance in the office environment. You will hardly watch an office TV sitcom without seeing it in the background. The familiar blue plastic jugs neatly placed beside the cooler in a neat row with their shiny stickers facing outwards. Pictures of mountains with water running down the side of them assure you that the water inside is fresh, clean and pure. So you drink without giving it any thought, happy that you are not drinking that disgusting water from the tap.

But is this the best option? Are there better options? Let’s consider a few facts about bottled water and bottled water coolers.

1.       Bottled Water Source: In most cases, bottled water is simply filtered city water or well water. It usually isn’t being collected from a stream at the bottom of a mountain! Surprised? Don’t be. There are only so many ways to collect water and most plants are nowheres near a mountain.

2.       Filtration Used: The filtration techniques used to filter the water before its bottled are usually the very same types of filtration you can buy for your home or office: Carbon block, Reverse Osmosis (RO), Ultraviolet (UV) Sterilization. Why pay someone else to filter your water and deliver it?

3.       The Coolers: Greater than 95% of coolers used are reservoir style coolers. What does that mean? It means the water is cooled inside an open reservoir which is air vented. Whatever is in the air ends up inside the water cooler. YUK! Algae growth, dirt, dust, chemicals and other nasty contaminants will find their way inside the cooler and here is where they stay until you pour a glass.

4.       Safety: Bottled water is becoming a concern from a safety perspective in the work place. For some, lifting a large jug (40 Lbs!) is simply dangerous. Injuries to backs have been reported and employers are becoming increasingly aware of the costs of workplace injuries.

5.       Cost: The cost of your water program doesn’t stop with the cost of the water itself. Count up the additional costs that are tagged onto the bill: Bottle Deposit Fees, Semi Annual Sanitation, Cooler Rentals and so on. What an expense!

These are just a few factors to consider before signing a contract for bottled water. But what are the other options? Look at Point of Use (POU) solutions like:

·         Bottleless Water Coolers (ie: The ION by Natural Choice)

·         Under Sink Filtration

·         Portable Filtration (ie: Lifesaver water bottle)

Bottled water does have its place. There are many locations where water is not suitable for drinking and filtration is too costly. Also, lack of available plumbing or high cost of installation make filtration a non-viable option. If bottled water is your only option, ensure your cooler placement is not near or susceptible to contamination and always maintain a good sanitation program.

To find out what drinking water options are suited well for your business or home, call National Water to discuss you needs.

Boil Orders and Drinking Water

We don’t realize how convenient it is to open a tap and pour a glass of water until we have a boil order put in place. It can be a nuisance to have to boil our water or purchase bottled water but don’t forget how fortunate we are to have municipal water supplies that are closely monitored and a warning system put in place to protect us from contamination in the rare event this happens.

Here are a few reminders to keep in mind in the event your water supply is under  a boil order:

·         Don’t take risks! There is a reason why the boil order is on. Don’t assume it is ok.

·         Do not use the water for washing fruits and vegetables.

·         Use bleach with no fragrance or additional chemicals to sterilize water. 1/8 teaspoon per gallon of water will provide you with safe water for washing and other uses.

·         When washing hands, it is good practice to use alcohol based hand sanitizer after washing.

·         Once the boil order is lifted, flush your lines adequately to ensure any potentially contaminated water is purged out of the system.

Bacteria Filtration

With advances in filtration and the proven disinfection technology of Ultraviolet Sterilization, homeowners and renter alike have more options than ever before for protecting their water supply from bacterial contamination. These technologies can bring peace of mind and convenience when a boil order is in place. With NSF approvals for bacteria, virus’ and cysts, we would all do well to at least explore these options to ensure safe drinking water for ourselves and our families.

Ultrafiltration (UF) – Uses hollow fiber technology to mechanically filter out dirt, sediment, bacteria, virus’ and many other contaminants. Filters as low as 0.01 microns. Some units are NSF or WQA approved.

Ultraviolet Light (UV) – Uses a high dose of UV rays to scramble the DNA of the bacteria preventing it from reproducing.  The bacteria eventually dies off on its own and poses no threat.

Microbiological Barrier (MB) Carbon Blocks – Using advanced technology, these point of use filters (typically installed under the sink) are extremely effective at bacteria removal. Boasting a 99.9999% reduction of bacteria, 99.99% viral reduction and 99.95% protozoan cyst reduction, MB block technology will be a technology of choice for those wanting a hybrid filter. Not only will it give you sediment, chlorine, taste and odor claims, but it will ultimately give you safe water.