5 Problems With Installing a UV Under Your Sink

First of all, why do you want an ultraviolet light on your reverse osmosis system?  Likely you will say that you want UV so that you can make sure your water is pure and free of bacteria.  A reverse osmosis system filters down to below .001 microns, but the smallest bacteria is larger than .01 microns, so theoretically, a RO system should not allow any bacteria to pass through.  However, if you look at almost any reverse osmosis system manufactured by any credible manufacturer, you will find that it says “Not for use on water that is not microbiologically pure.”  This is because a RO system has mechanical seals and o-rings that could become compromised or fail, so you should not rely on reverse osmosis for bacterial purification.

Problem 1:  Even if your water is contaminated with bacteria, you still bathe, shower and brush your teeth in it.  A couple of years ago, I showered in contaminated water in Haiti and got infections in both eyes.  It wasn’t fun, I can tell you for a fact.  If you have children or grandchildren, you know that they drink from anywhere, even the bathtub.  An ultraviolet light on the RO system does nothing for the rest of the water in the home.  You would be better served with putting an ultraviolet light on the incoming water supply to treat the water before the reverse osmosis system, so that you are not installing the RO system on water that is microbiologically contaminated.

Problem 2:  An ultraviolet light on a reverse osmosis system under your kitchen sink heats the water as it sits during the day or night.  It’s almost hot enough to make your coffee in the morning!  You could turn the UV light off, but then you could not be sure if your water was pure and turning the bulb on and off would shorten bulb by by up to 300% – not a good idea.

Problem 3:  The heat generated by the UV light bulb can weaken the fittings, embrittle plastic tubing and create a leaks in many circumstances.  That’s really pretty undesirable in most modern kitchens. Imagine comeing down in the moring and finding a swimming pool where your kitchen used to be.

Problem 4:  To put a UV under your sink, you need electricity.  I have heard people say “I have electricity to my garbage disposal” and they do, but your UV system will only work when you turn your garbage disposal on (not a good idea).  You need to run an additional electric line to the ultraviolet system and that can often be a problem.

Problem 5:  Most undersink ultraviolet systems are cheap plastic Asian Import models.  They are very unreliable. I’ll be kind and just say that they inherently have a lot of problems, not the least of which are leaks.

So, if you want a UV for use after your reverse osmosis system, the odds are, once you weigh the pros and cons, you will decide against it.  Many people opt to install a ultraviolet system on the incoming line to their home so that all of the water in your home is bacterially pure.  However, in addition to Ultraviolet Disinfection, there are two additional technologies that are extremely effective at disinfecting water.

Pulsar Intercepter Filter:  The Pulsar Disrupter Filter uses Electro-Adhesion to remove bacteria, virus and cysts “AHEAD” of the Reverse Osmosis Membrane.  It also has PAC (powdered activated carbon) and Agion Silver on the media to remove VOC’s and prevent bacteria from growing on the media itself.  This filter is used ahead of any other RO filters so as to keep bacteria out of the system, whether you know you have it or whether you just want to be safe and sure.

Pulsar Quantum Disinfection: A Pulsar Quantum Disinfection Filter uses a revolutionary, patented technology that uses quantum mechanic principles of electron movement to create surface catalytic sites to destroy microogranisms up to 99.999%.  This should be the last filter in an RO system and is extremely effective at removing hetrotrophic and pathogenic bacteria which are commonly found in RO tanks. With Quantum Disinfection, a Ultarviolet light is totally unnecessary.

Note:  This blog was initially published in 2014 and was just updated.


This article has 20 Comments

  1. Thank you for the info on U. V systems location. I use Severn River (Ontario Canada)water thru a UV and am installing a R.O. system and was about to mount the R.O. ahead of the U.V. as shown on most Water Purification Companies web sites. Thinking about it over night I said to my self, currently I’m killing the bacteria on all my incoming water, now if I change I’m only treating the drinking water not the rest. Your site has just verified what I was thinking and given me confidence to go ahead. I will have it tested of coarse. The UV heat issue is also very real and very interesting. My unit is in the basement, 20′ away. Andy

  2. You sell the Polaris UV-1C unit which appears to be positioned as an add-on to a reverse osmosis system. What application would that be used for if not undersink?

  3. I used to have an undersink unit. I made the mistake of using the plastic tubing which did rupture over time. I do how ever feel compelled to try again. Would it be possible to run stainless steel lines at least 15 to 20 inches long on the inlet and outlet to the ro faucet so as not to degrade any other plastic parts?

  4. We have two new products, both of which will be released between now and June for undersink drinking water systems.

    One is called the Silecte inline filter and the other is the Pulsar inline filter. Both kill bacteria better than UV! Watch for them. Stainless steel lines? Not a good idea in my opinion…

  5. Hello,
    Why do you say to install the uv light at point of entry?
    I have very hard water, 42 grains. These are very large particles that the uv light may not be able to penetrate. Would it not make more sense to install it after all other treatments/filters, such a water softener etc?

  6. Thanks for your very informative discussions.
    I am planning on starting a water bottling filling station with an RO system and UV sterilization . The source of the water is from a well in Ontario, Canada. The water hardness is 7, the iron(ppm) .08, the Ph 7.5, TDS 280. Most of my customers will be in a country setting on wells. I will be processing the water in advance of distribution. Storing the RO water in large holding tanks and then distributing it from the holding tanks. Question Should I put the UV before the RO system. I am looking at a Vectapure RSX Lite 300 GPD RO system.
    Thanks Vince.

  7. Vince,

    Are you planning on not selling much water? The reason I ask is because that is a very light-duty system and with your water temperature, it will make about 150 gallons per day (at best). Is that enough? How big are your holding tanks? I would not use UV – I would use Quantum Disinfection. The disinfection should be the very last thing, although if your water is microbiologically unsafe, you may want to do both. You can contact me at mark@uswatersystems.com

  8. Hey Mark,

    I’m not sure about UV being last. I treat rainwater and had particulate -> carbon block -> UV

    Using Poly particulate filters so bacteria wouldn’t grow, but the carbon block would clog from growth.

    Calling Pentek they told me I did it wrong. It should be particulate filter (I have two, last stage is 1 micron) then UV then into carbon block.

    Sure enough I redid system and my 0.5 micron 4.5×20 carbon block lasts 3x as long now.

  9. hello mark, one thing i can not agree is that the UV systems from Asia is not as bad as you think. please kindly trust the Chinese made products.

  10. Jason,

    There are some good Asian made systems, but many are not. I guess I am just against UV under a sink, period! The negatives are not worth it, especially when there are better ways of disinfecting.

  11. Mark in your reply of Oct 19, 2017 you say that you are “against RO under a sink”. Did you mean UV under the sink (the topic of the blog) or are you saying that RO should not be installed under the sink?

  12. I live in an area where toxic blue algae blooms create water alerts from the Cyanotoxins. UV seems to be effective against this. How about the Pulsar filters? Thanks.

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