UV water purification - health risks?

[yannis]

Hello! I saw on this website an old forum topic - like 15 years ago, where some ppl by and large were discussing how this technology works. What bothers me as a potential consumer , considering buying a home system for drinking water - is it totally safe? I trust that it kills all organic impurities as stated, but what about radiation? Even sun UV which must be weaker - since it doesn't kill bacteria etc. in ponds e. g. is said to be dangerous for skin and eye exposure, this is what causes sunburn and when stronger - as in such a device - clears germs by destroying their DNA. Then what about the water we drink - if it has been irradiated, won't it carry that same radiation when we devour it and can't it damage consumers' DNA as well? Else, if water does not absorb radiation, then where does it go? Once it has been produced, it can't just disappear, I guess it shall saturate the closest surrounding objects - the water pitcher walls, the kitchen cabinets and countertop - and emit from them?

 

[Harald Kapp]

Else, if water does not absorb radiation, then where does it go? Once it has been produced, it can't just disappear

UV "radiation" is light. It "disappears" as the light energy is converted into thermal energy (heat). You will not find any trace of UV light in the water once the light source has been turned off or the water has been transported away from the light source.

This is completely different from ionizing radiation (e.g. gamma rays etc.) which physically changes the irradiated material and makes the material actively radiating. This kind of radiation therefore persists even when the original source of radiation is turned off.

 

[davenn]

moved to off-topic forum as it isn't an electronics topic


Harald ....

This is completely different from ionizing radiation (e.g. gamma rays etc.) which physically changes the irradiated material and makes the material actively radiating. This kind of radiation therefore persists even when the original source of radiation is turned off.

this is not correct ...... yes, it can change the material, but it DOESNT leave it radioactive.

EDIT

I was rushing to type that as I was heading out the door to work

Ionising radiation, eg. alpha, beta particles, gamma and x-rays, does not leave a object/person radioactive. in non living material they are just absorbed and increase the heat of an object.
In living tissue, they disrupt the molecular bonds in/between cells. This is what leads to the formation of cancers etc.

For an object to become or be radioactive, there MUST be nuclear decay. An atom must already be unstable.

Ionisation = loss of electrons = is not radioactivity
nuclear decay (radioactivity) = loss of particles from the nucleus …. alpha, beta, gamma, x-rays


Dave

 

[davenn]

UV "radiation" is light. It "disappears" as the light energy is converted into thermal energy (heat).

This needs correcting as well
Many minerals glow a different colour or much brighter under UV light, a number of my rock and mineral samples do.
The exposure to UV light causes electrons in those mineral to move to a higher energy level. When the electrons return back to their lower energy level
they emit a photon of a given wavelength.

This is not ionisation, nor is it radioactivity

material actively radiating

This, of course, is not radioactivity as in the normal use of the term, otherwise EVERYTHING in existence above 0K is radioactive.
You, me, the keyboard you are using, your car, your house, the veges in the garden etc, etc because they all emit photons in the IR wavelengths

As said in my last post radioactive;radioactivity, is used to describe nuclear decay


Dave

 

[shrtrnd]

yannis,
Your post is concerned with safety.
I've worked in water treatment plants, they use UV light to disinfect with no problems.
The primary issue, is that you do not look directly at the UV bulb, as they can damage your eyesight.
I would ASSUME a manufacturer would shield the light from the bulb so an owner wouldn't be looking directly at it.

 

[Bluejets]

I would ASSUME a manufacturer would shield the light from the bulb so an owner wouldn't be looking directly at it.

Assumption is correct.
Seen many of these units mainly in outback or remote areas of Aus and also common use in homes in Thailand.
Example of just one of the many housings below.