UV-A, UV-B, UV-C, what are their effects on water, micro-organisms, health?

All these happy photons are part of the light spectrum, they are electromagnetic waves, but our eye does not see them. They are at the bottom of the spectrum, opposite the infrared.


Let’s start with the most abundant, and by far, the UV-A, which represents 5% of solar radiation. They are harmless, but can help fight skin diseases. They are globally essential to our balance, and cause only a slight tanning of the skin after a few hours of exposure. Exposure of more than a few hours per day is not recommended, although there is no clear evidence of long-term harm.

They are widely used in industrial products: polymerization of glues, drying in printing and screen printing, drying and polymerization of nail polish, fluorescent light in nightclubs, etc…

Purificateur d'eau LaVie

Purify your tap water with LaVie UV-A

LaVie® UV-A water purifiers operate without filters or maintenance and allow you to purify your tap water in 15 minutes.

They use an innovative, patented technology exclusive to LaVie®: the photolysis of chlorine by UV-A radiation.

This treatment allows the removal of chlorine and its by-products, chemical compounds such as certain pesticides or traces of medication, tastes and odors that can be found in tap water.

The result, very qualitative, allows to draw a definitive line on the consumption of plastic bottled water.

The carbon footprint associated with the manufacture of the UV water purifier’s aluminum tube is neutralized in a few days of use compared to the equivalent consumption of water in plastic bottles.


UV-B is clearly carcinogenic in high doses, hence the increasingly strict regulations on tanning booths because of the cases of skin cancer in particular. They are responsible for “sunburn”, which can occur after only 30 minutes of exposure for fragile skin.

The atmosphere filters out most of it, which allows us to face the midday sun without too much risk.

They are very little present in commercial products, except for some reptiles and tanning booths.


UV-C is deadly to humans and just about everything else on the planet. There are none on earth, because they are blocked by the ozone layer (let’s hope it stays there, otherwise we will have to live underground…).

Man manages to produce them with mercury lamps or leds, mainly for their effects on bacterial DNA.

Learn more about UV: https: //fr.wikipedia.org/wiki/Ultraviolet

UV and water

So let’s focus on the water, and the unwanted living organisms inside.

The UV-C are used in sterilization, they can affect the DNA of bacteria and make it mutate. This blocks bacterial division.

If you drink water loaded with UV-C flashed bacteria, you will be drinking these bacteria, most of them alive, but with the guarantee that these bugs will not reproduce during digestion. Thus, you will be “saved”, but you will not improve the taste, the smell, or the physico-chemical aspects of the water. That’s why we talk about sterilization (and still, to kill bacteria, you have to triple the dose, and for some viruses multiply it by 10).

You can therefore purchase a UV-C bottle if you wish to consume water from a lake or river, provided that it is not loaded with chemical elements, pesticides, traces of medication, etc…

Some brands document them as water purifiers, this is entirely false. In particular, bad tastes and odors in tap water are mainly caused by the 500 chlorine by-products, some of which are known carcinogens, which will not be affected by the UV-C “flash”. In this respect, even a “vulgar” carafe filter does much better

Moreover, the major players in the water industry use UV-C for their rapid action, but at the end of the treatment, just before chlorination for transport in the public network.

But, when I see French companies equipping themselves with UV-C led treatment under the sink at 1300€, I cry scandal: there are no bacteria in the tap water in France, there is no point in trying to eliminate them…

It’s as bad as buying a water softener (1000€, very polluting) to improve the taste of water: who prefers to drink salty water passed through resins and plastic to avoid absorbing calcium?

So, one last reminder, UV-C cannot “purify” water, unless you believe that purifying means killing a bacterium to drink it dead, I’ll let you conclude.

UV-A is used for its bactericidal properties in the SODIS (solar disinfection) process developed by ewag and widely used in developing countries. Plastic bottles are exposed to the sun for several hours to eliminate pathogenic germs, which greatly reduces cases of dysentery, for example.

désinfection solaire

Solar water disinfection, also known as SODIS (for Solar Disinfection), is a method to disinfect water using only solar radiation and polyethylene terephthalate (PET) bottles: source Wikipedia

UV-B is hardly ever used for water treatment because plastics and glass are opaque.

Is LaVie different?

Using UV-A for its bactericidal side is not patentable, as it has been known to man of the art for decades, so we have patented something else.

Fasten your belts, we attack the dive in this magnificent innovation. We’ll have to go through a quick explanation of what an advanced oxidation process is, a family that LaVie is a part of.

The technique is simple: an active ingredient is sent into the water (hydrogen peroxide in the most common processes, i.e. H2O2), which is then destroyed by UV photon bombardment. This explosion generates radicals, which by rebound will decompose everything that is not water into simple elements.

The environmental impact of osmosis systems

Now let’s detail the environmental impact: Four filters and a non-recyclable membrane per year, and more than 60% of the input water goes into the environment as concentrated soup. You will of course pay for this wasted water in your bill.

You still want to buy a reverse osmosis system? Test our LaVie system beforehand, we work miracles on water with a high mineral content, and you can return the product if it doesn’t suit you. There is no installation, no filter to change, no bacterial pollution to worry about, no trace of chlorine or bad taste.

Advanced oxidation processes (abbreviation: AOP), in the broadest sense, are a set of chemical treatment procedures designed to destroy organic (and sometimes inorganic) materials suspended or in solution in domestic, urban or industrial effluent water, by oxidation via reactions with hydroxyl radicals (HO-) Source Wikipedia

Pesticide dans l'eau du robinet

Still too many pesticides in tap water. Source: Générations Futures

Water companies use these very expensive processes to remove persistent substances from wastewater: female hormones (beta estradiol from the contraceptive pill), endocrine disruptors, pesticides, traces of drugs, etc…

But no one had thought of using this type of treatment for tap water, even less with UV-A instead of UV-C, and even less with the active ingredient chlorine contained in tap water.

We have thus created the first domestic advanced oxidation process that is as safe and effective as its ancestors. The novelty consists in flashing the chlorine in the tap water with UV-A radiation, which is transformed into oxidizing radicals (O, O3, H2O2, H-, CL-) and thus reduces the chemistry around it into by-products, thus increasing the oxidizing power of the chlorine by a factor of a thousand to a million, while making it disappear, it was necessary to think of it!

By the way, living bodies (bacteria, viruses etc…) are riddled with holes created by these violent exchanges and cannot come out of this treatment alive or in one piece.

Let’s conclude: avoid UV-C based products if you are not a wilderness camper or an inhabitant of the Philippine islands, do not expose yourself too often and too long to the sun for your health, favor its indirect light, and do not forget that the pollutants of wastewater are appearing in drinking water, because guess where the discharge of wastewater treatment plants is made: In rivers, streams or groundwater…which we then consume in the form of bottled or tap water.

Thus, protecting oneself from micro-pollutants can probably be interpreted as a precautionary principle, but would you think of drinking drugs or pesticides, even in very small quantities?

Similarly, do you think that drinking chlorine, a biocide in tap water, has no effect on the bacteria in your trachea?

You are a “consumer”, it is up to you to judge.

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