The Belfast Trust does not anticipate the “worst-case scenario” of replacing all the water pipework at the long-awaited maternity hospital, which would cost up to £9m and take as long as four years.

An official from the trust made the comments on Thursday during a briefing to Stormont’s health committee on the problems with the Royal Maternity Hospital project.

The hospital is already 10 years behind schedule and has been beset by problems.

Potentially harmful bacteria, known as pseudomonas aeruginosa, was previously detected in the water system, while in November, Health Minister Mike Nesbitt revealed there was an issue with medical gas pipework. Earlier this week, he said the gas pipework problem would cost £50,000 to fix.

Regarding the bacteria in the water system, an interim report on the issue compiled by experts is being reviewed by the Belfast Trust and a series of recommendations in it are being implemented.

Maureen Edwards, chief executive of the Belfast Trust, said that once further testing is carried out and a review undertaken by external consultants, there will be three potential options going forward.

Ms Edwards said the first would involve “minor localised remediation works”, which would take between three and four months and cost around £750,000.

The second option would be minor works in areas of the hospital that are to serve the most vulnerable patients, such as in theatres and the neonatal unit.

The final option would be a “full replacement of all domestic water pipework”, which could take up to four years and cost between £7m and £9m.

She added: “I should stress that based on the latest sampling results, and subject to the success of the revised flushing regime that we are going to implement, [neither] the trust nor the independent report at this stage would anticipate an outcome where that worst-case scenario of full replacement of pipe work would be the preferred route. “

The trust’s chairman Ciaran Mulgrew added: “I would very much doubt that we will be at the worst-case scenario.

“I think we will be in option A or B, but we can only make that decision in light of the best scientific evidence that is given to us, and then by listening to the clinicians who will be responsible for the safety of the mothers and children within the hospital.”

It is unclear when the hospital, the cost of which has spiralled from an initial estimate of £57.2m to around £100m, will become operational.

Last month, there were calls for an independent inquiry into the delays to the project, the handling of which has been described as an “omnishambles”.

Ms Edwards told the committee: “I recognise, and I indeed share, the health committee’s frustration and the public’s frustration with the delays and cost increases associated with the maternity hospital scheme.

“Our focus at this juncture is obviously to safely open a 21st century hospital that the mothers and babies of Northern Ireland deserve, but we know that needs to be safe.”

She added that there will be a “great deal of learning” to be gained from problems with the project.