Chlorothalonil and the filter technology from FEWATEC


The FEWATEC Cristal water filter removes chlorothalonil.
Chlorothalonil was for years one of the 10 most sold fungicides in Switzerland
It has been used as a broad-spectrum fungicide on both agricultural and non-agricultural land (e.g. golf courses).
In 2019, the Swiss population became aware of the contamination of individual drinking water samples with this fungicide. In the drinking water samples objected to, the measured values of the detected chlorothalonil metabolites were above the legal limit of 0.1 µg/liter. Since 1 January 2020, the use of Chlorothalonil has been prohibited in Switzerland.

What are metabolites?
Metabolites are degraded substances. The term usually refers to substances that are created from a biochemical process. This means that there is nothing left of the original substance, only its degradation products.
A -->  B and C and ....

A is the original substance (in this case chlorothalonil), B, C and possibly other substances would be the degradation products.
More than 20 different degradation products are known of chlorothalonil. However, Chlorothalonil itself has never been detected in drinking water, as it sticks to the soil particles and thus does not enter the water.

How well does FEWATEC Cristal remove the metabolites?
According to an assessment by EAWAG (Swiss Federal Institute of Aquatic Science and Technology), a statement about contamination can be made by determining 2 metabolites (metabolites R471811 and R417888) in a drinking water sample [1].
FEWATEC AG had the effectiveness of its FEWATEC Cristal water filter tested in a neutral laboratory.
In one test a water sample with a very high metabolite concentration (approx. 1 µg/l) was contaminated and passed through our filter. An analysis of the water after filtration showed that about 90% of the metabolites were filtered out.
Of the known drinking water treatment processes (UV treatment, ozonation, other oxidation processes, activated carbon and reverse osmosis) the activated carbon treatment and reverse osmosis show the best results regarding the removal of chlorothalonil metabolites.
Reverse osmosis is the most effective. However, reverse osmosis processes are more complex and require a high operating pressure.
Activated carbon filtration is technically very simple.
The FEWATEC Cristal filters contain, among other filter components, activated carbon made from coconut shells and specially manufactured for drinking water treatment.
[1] EAWAG, The Water Research Institute of the ETH Domain, fact sheet, February 2020