There are fears that a reservoir that supplies water to Belfast's restaurants, hospitals, schools, offices and households could become contaminated due to a nearby drilling for oil and gas.
For more than a year the Stop The Drill campaign has tried to highlight the problems associated with an exploratory drill, located just 380 metres uphill from Woodburn Reservoir, near Carrickfergus, being undertaken by Infrastrata.
Permission for the drill was granted on the site, which is leased from NI Water, to the oil exploration company without consultation, according to those behind the campaign.
The controversy will be debated by Belfast councillors tomorrow at City Hall.
Fiona Joyce from the Stop The Drill campaign said everyone who receives water from the reservoir should be concerned about the project.
She told the Belfast Telegraph: "The Woodburn reservoir outside Carrickfergus supplies Dorisland Water Works, which feeds water to over 1,900 streets, from Ballycarry right down to Belfast city centre.
"Following a freedom of information request we received a map showing exactly where the water from the reservoir goes. It supplies hospitals, health centres, schools, offices, residential areas and all the eateries in central Belfast.
"We feel that the drill potentially could contaminate the water supply and everyone supplied by it should be aware of this.
"A motion has been tabled for debate in the City Hall at 5pm on Tuesday, proposed by the Green Party and seconded by the Ulster Unionist Party.
"We lobbied hard for this debate to go ahead and are hopeful that it will raise even more awareness of the potential hazard the drill could pose."
Woodburn Reservoir supplied 705 streets across Belfast, 532 streets in Carrickfergus, 576 in Newtownabbey, 59 in Larne, 80 in Whitehead, four in Ballycarry and one street in Antrim.
Ms Joyce added: "The decision to grant InfraStrata rights to drill 380 metres from our water was made without consultation.
"The right to participate and be informed is being violated. The risks of exploratory drilling are detailed and well documented and it appears that the need for intense scrutiny in relation to this sensitive site has been avoided." Meanwhile, a partner company that was putting up funding to support the drilling has pulled out of the project, leaving the drilling company short of almost £3m.
It has been revealed that Larne Oil and Gas Limited had run into "funding difficulties" and "will no longer be participating in the project".
However, Infrastrata says it is committed to the project and is in discussions with a number of other parties to secure the £2.8m lost by Larne Oil and Gas pulling out. Infrastrata also said that all the "regulatory approvals and other permits" were in place for work to begin this winter, but the company added that the timing depended on getting a drilling slot for the rig and completing the funding.