ultraviolet water purification..

[mike]

we have had our well water here test positive for coliform bacteria more then once so we decided to have a whole-house ultraviolet water purification system installed by Rainsoft.. This was after i heard all the bad things about rainsoft.. I honestly think all these water purification installers are crooks.. The guy had to come back to my house 3 times because the pipes were still leaking.. I asked the guy about his past and he said he never even went to school to learn this.. What kind of friggin people are these guys hiring?

But i would like to know is this system really effective in killing all the bacteria in the water? The water seems to move through it pretty fast.. Also, i was doing a google search on this and a science teacher brought up the fact that this type of ultraviolet on water could possibly cause cancer in humans.. Is there any proof of this? I was pretty piszed when i read about that.. Our government will probably tell us 20 years from now that it causes cancer..

thanks mike

[Fred]

I am no expert on the ultraviolet method of water purification, but have never heard about the cancer causing aspects of it. I tend to ignore a lot of the cancer scares we get in today's media. If you feed rats enough honey or any other benign food, I am sure that some of the rats would develop cancer of some other abnormality. But, would they have developed it anyway, even without the honey? Who knows? Every week there is some sensational report that says eggs, or something else are bad for you and then within six months, there is another report that eggs or whatever are good for you and we should eat more of them. Large Cities are using ultraviolet to purify drinking water more and more these days, so one would think that it has been investigated pretty good for it's effectiveness.

[CBHvac]

purification

As you found out...you have a bad installer...it happens. Bad thing is, you paid for his training.

The UV-C band units I sell, have an 80% FIRST pass kill rate and thats with air, moving more in volume, and in not as tight an enviroment as the UV system you have for your water...so...I would say, they are VERY effective.

None I can find, and in fact, the opposite.

In fact, (granted, its from a company that sells the units, but you know, that info now has to come from a 3rd party, in this case, a local college) having a UV system on every unit I install (AC) and 2 units in my home, it makes even more sense to install one for the water too..I would not worry one bit about it...

Sheesh...depending on where you live, the very air you breathe is causing SOMETHING to go wrong..

[TKM]

purification

The UV generated by your water purification unit is what's called short wavelength or germicidal UV and it's very fast and effective at killing viruses, bacteria and other nasties. If the unit is sized for your water system and operating properly, it will work and the manufacturer's literature or web site should tell you if you have the right unit for your application. To be absolutely sure, sample the incoming and output water and have it tested.

Short wavelength UV can damage skin and eyes so you should not expose yourself to UV radiation from the lamp. An automatic shut-off switch is usually part of the unit so the UV lamp will not operate if the unit is open. The purification device should also have safety glass in the inspection port so the UV is kept inside the unit. Usually, some visible blue light can be seen through the glass, but the harmful UV is filtered out.

Short wavelength UV is associated with skin cancer. If you expose your skin to the UV from sunshine or certain electric light sources over time and particularly if you have had severe sunburns when you were young, your chances of skin cancer go up. But your UV water purification unit does not expose you to UV and nothing is done to the water as it goes through the unit that would make the water cause cancer.

TKM

[Ian Stirling]

There are none, as it's the UV that causes (skin) cancer. If the unit is competantly installed (a blueish glow visible anywhere is bad news) there should not be any risk. There is certainly no risk when it comes out of the taps.

The way to rate UV systems is how long the water is exposed to the UV, and how intense it is. This is measured in units like s * mw/cm^2.

Exposing stuff to UV for ten times as long is as good as ten times the power for a tenth of the time. Various stuff requires different amounts of UV to kill it. The hardest stuff to kill is generally spores.

[jriegle]

Good post. I would also like to point out that the short wave UV is also good at chemically altering the glass of the lamp itself causing the sort wave emission to be reduced over time rendering the lamp ineffective at killing the baddies even though lamp appears to be operating normally. You should replace the tube periodically even though it has not burned out. The guys over in sci.engr.lighting probably can explain this better. John

[Gary Slusser]

"mike" wrote

purification

installers

Crooks because of poor plumbing skills leading to water leaks in plumbing they did to install the light! I'd say it was due to their pricing but... You ask questions about their hiring practices after reading about them and buying from them after that anyway! ummmm

brought up

UV is one of the best means to treat for bacteria but it depends on a number of things as to how well UV works in a given application. Things like if the water needs pretreatment and you have it and maintain the equipment to allow the light to work as it should. Also, you have to replace the bulb in the time frame for the make of light you have. That's usually 9000 hours (annually due to the intensity falling off due to changes in the quartz the lamp is made of etc.) for all lights that do not have an intensity meter or metering circuitry; which is finally becoming popular with more and more dealers. I've been selling them since 1994/19955. And it depends on the class of the light you have; A or B with A being the only type I'll sell. The A lamp produces much more intense UV-C than the class B lights. Like 40K to 16K microwatts/centimeter squared when they are new, or the newest terminalogy, microjoules/cm2. And then there's the proper flow control to maintain the light's rated flow. So what light and any pretreatment do you have or need based on the raw water quality you have?

No, the teacher isn't explaining things correctly or is mistaken. UV for water is in the germicidal range of the UV spectrum; exactly it's 254.7 nanometers which is shortwave UV-C. If the light shines on you or in your eyes that's dangerous but then the light would be in a bad way and won't be treating your water anyway. If you have a viewport, the light emitted from it does not contain the invisible UV-C due to it being 'filtered' out by the material the veiwport is made of; which is usually thick plexiglass.

Gary Quality Water Associates