A new report from Geus, the Danish national geological survey of Denmark and Greenland, has turned up some disquieting findings.
Figures submitted by waterworks across Denmark to the Jupiter database reveal that 41.1 percent of the drinking water wells examined contained traces of pesticides or residues. In addition, 11.4 percent of wells had levels over the permitted levels of 0.1 microgram per litre, reports Ingeniøren.
By way of contrast, a similar report in 2017 found problems in 32.5 percent of wells and 10.5 percent over the limit.
A tighter checking regime
One of the reasons for the increase is that water suppliers are checking for a greater number of potential pollutants.
“In the new report we have been looking a bit deeper to include reserve and emergency wells that water suppliers might use if their main well is polluted,” said Anders Risbjerg Johnsen, a senior researcher from Geus.
Since July 1 last year it has been obligatory for water suppliers to check for dimethylsulphamide (DMS), a residue from the breaking down of the fungicide tolylfluanid and dichlofluanid. DMS has been in use since the 1950s in the production of fruit, tomatoes and ornamental plants.
Mixing the output
Another chemical that is now being monitored is desphenylchloridazon, a residue from a chemical sprayed on turnip fields until 1996. Last year it was discovered that almost every fourth well contained traces of the chemical, and in every tenth the concentration exceeded limits.
However, just because a well contains too many undesirable chemicals does not mean that the water in the consumers’ tap is undrinkable. A waterworks can reduce the concentration by mixing water from different wells.