Ms Armstrong said the fine was there as an important deterrent.
“We have long been supportive of NI Water’s efficiency savings but that does not mean they can ignore their responsibilities in relation to environmental accountability. That is especially true as it comes only months after NI Water was fined £40,000 for spillage into the Moyola River.
“Alliance has been speaking to residents in Killinchy about the long-term issues there and their concerns have now been borne out with the findings and subsequent fine.
“It is vital the company learns from its mistakes and does not repeat them. The last thing we want to see is a recurrence of the incidents.”