Delays to the opening of Belfast’s new maternity hospital after high levels of the bacteria pseudomonas were found in water systems will add to the already “eye-watering” costs of the project, Health Minister Mike Nesbitt has said.

Mr Nesbitt also revealed to MLAs that a review of how all health trusts in Northern Ireland monitor their water systems in hospitals is now being carried out.

Speaking during question time at Stormont on Tuesday, the minister said remediation work at the Belfast hospital is expected to delay its opening for a “very long time”.

The project to open a new maternity hospital at the Royal Victoria site has been plagued by delays for several years.

It had been expected the hospital would open next year when the Belfast Trust took possession of the new building in March.

However, during testing of its water systems, high levels of Pseudomonas aeruginosa (PsA) were discovered, leading the Belfast Trust to state the project is now facing a significant new delay.

Pseudomonas aeruginosa is found widely in soil and stagnant water.

It does not usually cause illness in healthy people but can pose a serious threat to people with weak immune systems.

Answering questions at the Northern Ireland Assembly, Mr Nesbitt said that before the contractor handed the building over to the health trust, samples were taken from the water supply.

DUP MLA Diane Dodds said the projected costs of the new Belfast maternity hospital had more than doubled (Brian Lawless/PA)

He said: “The results of these samples were reviewed and they did meet contractual obligations.”

After the building was handed over to the trust, the minister said the water systems were put into “operational mode” and further testing discovered significant levels of PsA.

He said the trust had since commissioned an independent review of the water systems at the new hospital.

Mr Nesbitt added: “Remediation works could significantly impact on timescales for occupation of the building.”

DUP MLA Diane Dodds said the projected costs of the hospital had more than doubled since the initial business case was presented.

Mr Nesbitt said: “Where I have a difficulty is that the contractor ran some tests, which were acceptable in terms of how these contracts are managed, but actually those tests were not replicating how that water system would operate once the hospital had been commissioned and was fully operational.

“When the trust did that (testing), that is when we discovered the levels of PsA were not acceptable and the problem has arisen.

“It is a very serious problem. It may take a very long time to fix the problem.

“It is a hospital that has been subject to delay after delay, for year after year after year.

“The consequence is that the price, the cost of building the hospital, is now eye-watering.

“When I first saw it written down on a piece of paper I thought there had been a typographical error.

“It is phenomenally expensive.

Alliance Party MLA Connie Egan asked how the Department of Health was monitoring the risk to water systems in other health settings (Liam McBurney/PA)

“Having to spend the money to fix the PsA issue, particularly if the costs fall to the trust, is going to put even more pressure on an increasingly pressurised budget.”

Alliance Party MLA Connie Egan asked how the Department of Health was monitoring the current risks within the domestic water systems in health settings across all the trust areas.

Mr Nesbitt said: “On foot of the pseudomonas issue which has arisen in the maternity hospital at the Royal Victoria Hospital, we are now reviewing how every trust monitors the water supply in all of their facilities.”

The new maternity hospital in Belfast is already several years overdue and is well over budget.

A Northern Ireland Audit Office report earlier this year said the hospital was originally expected to be completed by the end of 2015.

Three babies died following a previous outbreak of the bacteria at Belfast’s Royal Jubilee Maternity Hospital in 2012.