NI Water says it has no concerns about drilling at Woodburn Forest having any effect on drinking water in Belfast.
In a letter to Belfast City Council, the company's chief executive Sara Venning said she was "wholly satisfied" with assurances there was no risk to the public water supply from the exploratory oil well project being undertaken by InfraStrata at the wood outside Carrickfergus.
The drilling has sparked controversy, and protests have been staged at the site.
Several councillors in Belfast expressed concern earlier this year that the exploration could impact on the city's drinking water supply. As a result the council wrote to the publicly-owned utility company.
The council is also planning to hold a special meeting to address the issue, which Ms Venning indicated NI Water will attend.
And NI Water has agreed that chief executive Suzanne Wylie will engage on the issue with other relevant councils, as well as relevant departments and agencies.
Ms Venning told Belfast City Council in her letter that no fracking had been, or would be, allowed at Woodburn.
"This work is being undertaken by an independent company, InfraStrata, under a licence awarded by the Department of Enterprise, Trade and Investment (DETI)," she said.
"All work is subject to the approval and agreement of the relevant authorities including the Northern Ireland Environment Agency (NIEA), DETI and Forest Service. InfraStrata cannot drill a permanent well without obtaining planning permission, which is the responsibility of Mid and East Antrim Borough Council. NIEA have also issued a water order consent motion, allowing for the use of wholly conventional chemicals, in common usage throughout the world, in relation to the Woodburn site.
"A clause is included in the agreement with InfraStrata that prohibits using the technique known as hydraulic fracturing (fracking), both now and in the future."
Ms Venning said her staff was carrying out regular inspections at the site.
"I can also confirm that the drilling site is not within the catchment area of the Woodburn reservoir, which supplies water to thousands of properties, including some within the Belfast City Council area," she added.
"To provide further protection, a 'triple lock' system is in place in order to safeguard the local water catchment area - this involves securely sealing the drill shaft, amongst other measures.
"NI Water staff are also conducting regular inspections of the site to ensure that everything is being conducted as it should be."
Last month a protester was arrested at the site for allegedly obstructing workers.
The Stop The Drill protest has been backed by environmental campaigners, including Hollywood star Mark Ruffalo and human rights advocate Bianca Jagger.