The treatment of the sanitary hot water ( SHW) is very complex because this water is meant for human consumption. We thus can’t, as for the cooling  towers, use just any kind of biocide. Moreover, the vast majority of the networks concerned by bacterial problems are networks that have been used for several years and that are as a result difficult to integrally alter, or that wouldn’t probably stand the shock treatments considered.

Today the curative treatments have shown the limits of their efficiency and their many inconvenients. ( see: heat shock and chlorinated shock)
It now appears necessary to use preventive treatments that work continuously for the legionella appear continuously in the networks through the cold water in which they exist in very small quantities, but they develop quickly as soon as they meet favourable conditions (temperatures, still water, nutricients…)

The copper-silver ionization is not a miracle solution, but it allows to treat the networks continuously in the respect of the drinking quality of the water, without any major modification of the network. It also has a very good efficiency.

Restraints:
The treatment of the hot water networks demands the respect of the constraints associated with the drinking quality of the water. Indeed, if from a medical point of view, a water whose temperature exceeds 25°C is unfit for consumption, we must legally apply the drinking quality criteria of the cold water to the hot water according to the January 3rd 1989 and December 20th 2001 decrees.

It is interesting to notice that the French have a deficiency in copper trace elements, that are used by the body to fight a great number of diseases, copper is a component of many remedies, in particular in dermatology.
As for silver, the maximum rate set at 0,01 part per million, it will totally disappear thanks to the new European norms. This difference finds its explanation in an unjustified severity towards silver, for silver is for the moment subjected to the same norms as mercury, the latter being much more toxic! Is it because blends of mercury and silver were used by dentists or because there was a mistake in the chemical abbreviation of these compounds when the 1989 Decree was written (Ag+ et Hg+), or it is because of the application of the precautionary principle? The latest W.H.O. publications nevertheless explain quite clearly that the risk of suffering from silver poisoning is close to zero.  
Method :
The ionization chamber is set in parallel on the recycling loop just past the hot water production. The potentiometer is set to obtain a concentration in copper of about 0,5 ppm and of 0,005 ppm in silver. The device functions continually and releases in the water the quantity of copper and silver ions necessary to obtain a constant concentration. Moreover, the current’s polarity on the electrodes is reversed to obtain an equal wear of both electrodes and to limit their clogging up. The liberation of the ions is regulated according the principle of Nernst of a balance of  potentials between the potentiometer and the half battery red-ox formed by the electrodes in the water.
Maintenance :
The frequency of the maintenance is determined by the quality of the water ( its hardness). It is imperative for the electrodes to be clean enough to be able to release the ions. A fifteen minutes operation every two weeks is necessary for a hard water, and every four weeks for a fresher or well-filtered water. This intervention doesn’t require any special competence (no use of chemical products ) and is subjected to a quick training when you first start the device. 
Besides, a little copper measuring kit is provided to test the copper concentration and make sure that the norms are not exceeded. This test takes 3 minutes, we advise you to do it every two weeks.