UV Water Disinfection FAQ

  1. HOW LONG HAS UV WATER DISINFECTION BEEN IN USE ?
  2. WHO SHOULD USE UV WATER DISINFECTION ?
  3. HOW DOES UV DISINFECT WATER ?
  4. WHAT IS UV DOSE ?
  5. WHAT UV DOSE DO I REQUIRE ?
  6. CAN I DO MY OWN INSTALLATION ?
  7. WHAT ARE THE ELECTRICAL OPERATING COSTS OF A UV DISINFECTION SYSTEM ?
  8. DOES THE UNIT NEED TO BE ON CONTINUOUSLY ?
  9. WHERE DO I INSTALL THE UV DISINFECTION UNIT ?
  10. CAN I INSTALL A BYPASS VALVE ?
  11. I AM INSTALLING THE UNIT IN A COTTAGE ?
  12. I HAVE MUNICIPAL WATER – DO I NEED UV DISINFECTION ?
  13. IS WATER PRE-TREATMENT REQUIRED ?
  14. HOW LONG DOES THE UV LAMP LAST ?
  15. DO I NEED TO REGULARLY TEST MY WATER ?

HOW LONG HAS UV WATER DISINFECTION BEEN IN USE

The first recorded use of UV water disinfection was in 1906 with a municipal installation in Anon, France. Residential application of the process was given renewed interest during the 1950’s and has been growing at an accelerating rate ever since. The technological problems and uncertainties faced by the early users have all been resolved and today’s UV equipment is not only safe, but competitively priced, but offers low maintenance and low operating cost compared to other disinfection methods. It is the disinfection method of choice for most residential applications.

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WHO SHOULD USE UV WATER DISINFECTION

Any one who receives their water from a private well or surface water needs to disinfect. In many areas we can no longer assume the safety of our water source with the ever increasing effects of agriculture and industry.

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HOW DOES UV DISINFECT WATER

When disease causing microorganisms are exposed to UV light their DNA is disrupted, disabling the microorganism’s ability to replicate and cause illness.

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WHAT IS UV DOSE

UV dose is the function of both the intensity of the UV radiation and the length of time the water is exposed to the UV radiation. UV dose is expressed in millijoules(mj)/centimeter squared (cm2)

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WHAT UV DOSE DO I REQUIRE

UV disinfection equipment is being manufactured to a number of different dose standards and it is important to know the dose being used when flow rates are specified. The oldest standard still in use is the US Department of Health standard which recommends a dose of 16mj/cm2. This dose is still considered acceptable for applications where the UV disinfection device is used to treat for nuisance organisms that colonize filters and water softeners when used with municipal water sources. For many years the industry used a standard of 30mj/cm2 for primary disinfection. More recently leading authorities (including the US EPA and NSF) have adopted a dose of 40mj/cm2 for primary water disinfection. We highly recommend the 40mj/cm2 for all installations where the water source is a private well or surface water and a dose of 30mj/cm2 for all applications with a municipal water supply.

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CAN I DO MY OWN INSTALLATION

Where local regulations allow and you have basic plumbing skills UV systems and  equipment can be DIY installed. Please review your instruction manual or installation diagrams for more detailed information.

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WHAT ARE THE ELECTRICAL OPERATING COSTS OF A UV DISINFECTION SYSTEM

The UV system uses about as much electrical energy as a 40watt light bulb.

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DOES THE UNIT NEED TO BE ON CONTINUOUSLY

Yes, The UV lamp needs to operate for several minutes to reach full UV output. Excessive on/off cycling of the UV lamp will greatly reduce its life expectancy. Additionally, by having the unit on continuously the chance that untreated water will be consumed is minimized.

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WHERE DO I INSTALL THE UV DISINFECTION UNIT

UV disinfection equipment should always be the last stage of any water treatment system and should be installed so that both the cold water distribution system and the hot water heater receive the UV disinfected water.

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CAN I INSTALL A BYPASS VALVE

Yes, if desired a bypass valve can be installed.

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I AM INSTALLING THE UNIT IN A COTTAGE

UV water disinfection is becoming very popular for cottages and summer residences. If your UV system is not going to be in use for several months, you can shut it down during absences. Provided you disconnect the UV disinfection system from the AC power source and completely drain the disinfection chamber in areas where freezing temperatures are possible, the lamp should last for the full approximately 9000 hrs. When used in this manner the quartz sleeve should be cleaned annually and the UV lamp should be replaced after two years regardless of hours of use. We do not recommend disconnecting the unit from the AC power source in situations where the cottage will be used on a regular basis e.g. every weekend.

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I HAVE MUNICIPAL WATER – DO I NEED UV DISINFECTION

The majority of municipal water providers do an excellent job of providing a safe, reliable supply of water to their customers. If you have any reason to feel that your water provider is not in this group you may wish to install a UV disinfection system to provide additional water supply security for yourself and your family. If you are using a whole house point of entry activated carbon filter to reduce chlorine and other contaminates, then the use of a UV water disinfection device after the activated carbon filter is highly recommended as micro-organisms are known to colonize in these filter media. It is for this reason that many of the available countertop and pitcher filter devices recommend frequent media changes in their user instructions.

Also, if your water supplier has ever had occasion to post a boil water alert, then we strongly recommend you consider a UV water disinfection system be added to your home use water supply. A UV water sanitizer will eliminate the need to boil your water if those contamination issues ever occur with your water source.

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IS WATER PRE-TREATMENT REQUIRED

The UV disinfection is a physical process and the microorganisms need to be exposed to a minimum level of UV energy for effective disinfection. To ensure low maintenance reliable operation, the water to be treated must not contain any elements which significantly reduce the UV transmission of the water or elements which will form a deposit on the quartz sleeve which will lower the amount of UV light energy in the disinfection chamber. Water, which meets the following minimum guidelines, generally requires only an annual maintenance interval, consisting of lamp replacement and cleaning of the quartz sleeve. Quartz sleeves are generally replaced after 2 or 3 bulb replacements.

Turbidity < 1 NTU

Suspended Solids < 10mg/L

Colour None

Total Iron < 0.3 mg/L

Manganese < 0.05 mg/L

Hardness < 7 gpg

If you are unsure as to whether your water source meets the required minimum standards, we suggest you have a sample of the water analyzed by a local water testing laboratory. We highly recommend, as a minimum, the installation of a 5 micron pre-filter before all UV disinfection equipment. If your water needs pretreatment in addition to the 5 micron pre-filter we would suggest you consult with us or a local water treatment specialist who is familiar with water conditions in your area.

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HOW LONG DOES THE UV LAMP LAST

The UV output of the UV lamp decreases slowly with age and has a useful life of 9000 hours (375 days). Beyond 9000 hours the lamp output starts degrade rapidly and disinfection performance will be suspect. Ultraviolet disinfection units are designed to provide the specified dose up to the end of the useful lamp life. The integral lamp change reminder alarm will inform you of the necessity of changing the lamp. Operating the UV lamp beyond 9000 hrs will result in ever reducing disinfection performance.

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DO I NEED TO REGULARLY TEST MY WATER

Yes, even with an Ultraviolet disinfection unit installed, regular water testing is strongly suggested to verify the safety of your entire water distribution system.

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