Video: DfI water chief Linda McHugh says back-up plans in place for Derry drinking water in case of Mobuoy contamination

A two-way pipe is also being run from the Ballinrees reservoir in Macosquin to ensure security of supply for the city in the event of something going wrong.

The contingency measures were outlined by the Department for Infrastructure’s Director of Water and Drainage Policy Linda McHugh at a briefing of the Stormont Infrastructure Committee.

Sinn Féin MLA Martina Anderson asked Ms. McHugh about the situation at the Cloghole abstraction point which is downstream of the Mobuoy dump site and supplies 60 per cent of Derry’s drinking water.

“We want clean drinking water...I was talking about Mobuoy dump. We are very concerned in Derry in terms of the drinking water there and the potential contamination of water. We know the importance of having clean drinking water and everything that goes along with it,” said the Foyle MLA.

The DfI water chief said stringent measures have been taken to protect the river and that these precautions have proven successful to date.

“NI Water has worked very closely with the Environment Agency and the Drinking Water Inspectorate. It’s a very rigorous regime of testing at the abstraction point at Cloghole on the Faughan, a far higher regime than would normally be the case and so far there have been no issues even during the very big flooding in the North West,” said Ms. McHugh, referring to the severe flooding in the city in August 2017.

The DfI director outlined some of the steps that have been taken to make sure Derry has clean drinking water in the event of something going wrong at Mobuoy.

“That said they are not resting on their laurels. They reprioritised a piece of resilience work that they wanted to do on their drinking water supply. So NI Water was going to run a two-way pipe between Derry and Strabane.

"Now they are going the other way between there and Ballinrees which is further around the coast, so should there in future be any issues with the water being abstracted from the Faughan they will have the resilience to draw drinking water from another source until the problem could be solved.

"They also have clear water tanks at the site at Carmoney which is a few days supply. You know, that’s also giving them a buffer should anything go wrong. As I said, at the moment there’s no sign that the Faughan is being impacted,” she said.

Ms. Anderson said people were anxious about the potential impact on water quality.

“You can understand the concern that’s growing because you can’t have that volume of waste just left there so near a river. I have to say I‘ve heard different assessments from other people with regard to whether the water and the river has not been contaminated or is not nearer to being contaminated than what’s being suggested,” she said.

Ms. McHugh said DfI would continue to work with the Department of Agriculture, Environment and Rural Affairs and NI Water as they monitored the site.