In Europe, to date, with the exception of a few countries (Italy for example) there are no laws on the treatment of drinking water
The reference on drinking water quality in Europe is now defined through Directive 2184 of 2020, transposed by all Member States
The quality level of filtration systems is left to the individual company, just as the choice of maintenance protocol is left to the individual company.
In this short article we outline our guidelines for effective and correct maintenance of water dispensers
Why is periodic maintenance of watercooler and purifier necessary?
Consumable parts wear out over time and need to be replaced. This is quite obvious. An activated carbon filter becomes saturated over time and loses its adsorptive capacity. On the contrary, there is a risk that substances ‘trapped’ on the surface of the carbon may be released in ‘clusters’. The manufacturer is obliged to state and guarantee the lifetime of the product, both in terms of time and volume of water treated. To continue with the examples, the same applies to a UV germicidal lamp: over time, its ability to emit radiation in the C spectrum decreases and it must therefore be replaced.
Generally, drinking water treatment filters work on removing chlorine from water to improve organoleptic qualities, i.e. taste and odour.
Chlorine coverage, i.e. the presence of a disinfectant in minimal concentrations, meets the need to avoid microbial regrowth in mains water.
Microbial growth in point-of-use treatment systems is a very sensitive issue. Phenomena of back contamination, as well as contact with external elements, or with mains water with a low bacterial concentration can over time seriously jeopardise the quality of the water supplied.
The bacterial colonies that can form are found in areas where the water does not flow, as well as embedded in biofilm. One or more analyses of the water supplied by the treatment systems at the point of use are highly recommended to see if there is a drift of bacterial growth in the system
Which disinfection product is recommended?
Granted that we are going to intervene on systems where the incoming water is already potable, and that the focus must be on regrowth and biofilm phenomena, as always the answer can only be the result of extensive reasoning that takes into account many factors
Must:
- have the ability to destroy bacterial load and microorganisms in general
- remove biofilm
- Be easy to handle and use
- Not damage contact parts
- Not be hazardous to human health
- Be easily removable with simple rinses
- Have an acceptable cost
The most commonly used disinfectants, (including in combination)
Chlorine-based compounds, such as hypochlorous acid or free chlorine, although excellent biocides have two limitations, the first in their poor biofilm removal action. In the diagram below, it can be seen that a strong oxidizing action reacts with the protective surface layer (EPS) of the biofilm, not penetrating thoroughly. The action is sterilizing only the surface part, we stop at the second image
The second reason lies in the incompatibility with osmotic membranes. Chlorine ruins them irreparably. Lastly, we add from experience that the removal of odor and taste after the action of chlorine-based disinfectant can also be lengthy
Peracetic acid, has both biocidal and biofilm-solvent capacity, is highly aggressive and one must dose wisely concetration and contact time to avoid dangerous corrosion. We point out the danger of handling it with any toxic vapors.
Hydrogen peroxide has a lower biocidal action than chlorine compounds, but at the same time has a good biofilm-solvent action. It does not attack osmosis membranes is easy to rinse. Concentration and contact time are elastic without creating damage to the components. It is definitely our favorite
Ozone is a very good biocide, decays quickly so it is easy to remove, has good biofilm-solventing ability, but is extremely corrosive, and inside plants generates compounds with water-contact parts such that they create taste problems.
