Umnarj Paeratakul writes:
<Recently I read an advertisement from a company selling "water
purification system". The ad claims that they
have a machine that will shine a strong UV light to tap water, and the
water comes out "cleaned from germs". Can this be true? I thought that
UV does not penetrate well in water.>
Oh yes it does. I don't go to the beach anymore because the only reason I
liked it was to go swimming in the ocean. My parents used to take us to
the beach a couple times each summer when we were kids, and I stayed in
the water virtually the whole day, coming out only occasionally to eat
something and wait out the time to go back in safely, and (futile,
but...) apply some more skin lotion, that only at my parents' insistence.
But I don't go now, not at all - haven't in many years because the water
washes off sunscreen lotion and I burn horribly. To heck with the
supposed skin cancer risks of spending too much time in the sun we hear
about these days, it just *hurts*!!! I was barely out of childhood when
I decided that even glorious, wonderful ocean swimming is not worth such
unspeakable pain and blisters on my back, arms and legs for three weeks!
And it's the UV light that causes sunburn, isn't it...? Pesonally, I'd
believe this ad. But, on a slightly more scientific note, perhaps
there's a way you can get data on this machine's actual performance.
Contact the company who produces it and see what you can find out. Such
as how they do QC testing on it, what specific organisms they try to
kill with it in water, how much water penetration, how much time it takes
to kill the bugs, the populations they challenge with and percent kill,
etc., and make your decision from there. Also find out if anyone else is
using it and what kind of results they get.
Ummmm....may I ask why you would be using *tap* water in your lab? I've
only worked in a couple of labs, but my college labs used distilled water
for all experiments involving water, at work, deionized water. And if we
needed it to be sterile (work only, not school) we autoclaved it.
Yersinia<----creature of the Great Indoors