BAM-forurening af drikkevandet - Skal vi rense? - De Økonomiske Råd

Institut for Miljøvurdering BAM-forurening af drikkevandet December 2003
2 Abstract
In Denmark almost the entire production of potable water is based on ground water. How-
ever, Danish ground water resources are under pressure, especially from pollution with ni-
trate and pesticides. The pesticide metabolite 2,6-dichlorobenzaminde (BAM) is the pesti-
cide-related substance, which causes most problems for Danish waterworks. Thus, BAM has
been detected in 22 % of water works boreholes, exceeding the drinking water quality crite-
rion of 0,1 micrograms pr. litre in 7 %.
According to current policy, ground water should only be subject to simple water treatment
(i.e. oxygenation and sand filtration) before distribution to the consumers. Extended water
treatment, e.g. active carbon filtration, is consequently only allowed when all other options to
provide clean drinking water have failed. When waterworks have experienced serious pollu-
tion, this policy has often lead to massive investments in relocation of the affected ground
water extraction sites.
The purpose of this project is to examine, whether BAM is a case for deviation from current
policy by applying extended water treatment, i.e. active carbon filtration. This is examined by
reviewing the legal, technical and economic consequences of allowing extended drinking
water treatment.
The extend of ground water pollution is traditionally expressed as the percentage of affected
boreholes. However, the current project has linked data from borehole analysis to the iden-
tity of the waterworks that the boreholes belong to. Not counting boreholes polluted with
substances not readily eliminated during active carbon filtration, it is estimated that more
than 500 public waterworks (>10.000 m 3 pr. year) are affected by BAM, approximately 126 of
these having problems with the quality criterion. Data also shows that approximately 80 % of
the water works that have problems with the quality criterion, have such problems in more
that 1/3 of their boreholes, making the need for serious preventive action imminent.
The review of the relevant legislation and the limited Danish experience with active carbon
filtration of ground water shows that there are neither legal nor technical reasons for not
using active carbon filtration.
The economic analysis shows that using active carbon filtration to solve the BAM-problem
will be less expensive than relocation of ground water extraction sites, when there are no
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