Almost £20m in additional costs due to problems at two Belfast Health Trust buildings has been described as "such terrible waste".
Newly-discovered issues with the Belfast maternity hospital could add almost £10m to the project's spiralling costs, while the amount spent on repairs and rehousing patients at the Acute Mental Health facility has now reached £9.4m.
The Department of Health, which provides funding to the trust, has been approached for comment.
Daniel McCrossan, who chairs the Public Accounts Committee, said: "We can't see such waste, such terrible waste, within our public sector and then still go to London and demand more [money]."
The maternity building on the Royal Victoria Hospital (RVH) site is already tens of millions of pounds over budget and more than a decade behind schedule. The new costs mean the project will exceed £100m.
It is understood the latest problem at the maternity hospital has been caused by chemical flushing aimed at dealing with the original issue of bacteria in the water system.
The flushing process has caused damage to the pipework, with more than 2,200 defective valves needing replaced.
A report seen by the BBC estimates a repair bill of £7.8m, with an option of 24-hour contractor working bringing that close to £10m. Work to replace the valves is now under way.
McCrossan added that every pound counts because "it is public money".
"There needs to be very clear accountability here and we need a reassurance because we've sought this - when are these facilities going to actually open to benefit the taxpayer whose money has been invested in building it?
"When are patients going to get the benefit out of using these facilities which they're designed for?
"And ultimately, how much more are we going to stick sticking plasters over problems instead of grabbing the bull by the horns and getting these things done?"
The new maternity facility is due to replace the existing Royal Jubilee maternity hospital at the Royal Victoria Hospital, but the opening date remains in doubt because of the ongoing repair issues.
The building was handed over to the Belfast Trust in March 2024, but the discovery of the potentially dangerous pseudomonas bacterium in the water system and other problems has meant the hospital has remained closed.
An investigation by trust managers into the building handover and subsequent water system issues was launched earlier this year. The BBC understands it will report this month.
In Freedom of Information responses to the BBC, the Belfast Trust refused to say if the repair costs were being met by relevant building contractors or from taxpayer money.
In a series of questions from the BBC, the trust repeatedly answered: "The trust and its legal representatives continue to engage with independent experts on matters of liability and cannot provide a further update currently."
Belfast Trust also refused to say if it was involved in legal proceedings in relation to liability for repair costs.
The trust took possession of the five-storey building from the joint contractors, Graham Construction and Bam Ireland (GBHP), and then began a "clinical commissioning phase" - a process of ensuring a safe transition of service to the new site.
Just a few months later in July, the trust said that during testing of water outlets, high levels of pseudomonas aeruginosa were discovered in the water system.
Pseudomonas infection killed three babies at Belfast's Royal Jubilee Hospital in 2012.
The infection does not usually affect healthy people but infants and people with weakened immune systems are vulnerable.
A report into the latest problems at the new maternity building said there were several critical issues which could "compromise the long-term safety and operability of the building" if not addressed.
The thousands of valves being replaced showed "accelerated deterioration due to the existing chemical dosage regime" being used to flush out any bacteria, it said.
As many of the valves are concealed within the building, substantial sections of the ceiling will have to be removed to gain access, according to engineers in the document seen by the BBC.
Their report also said there was a risk of repair costs increasing further and the estimates did not include costs associated with professional fees.
In a statement, Graham Construction said GBHP successfully handed over the hospital to the trust "in accordance with its contractual obligations".
"Prior to handover, all water quality samples tested within the facility were confirmed to be free from pseudomonas aeruginosa (PsA). These tests were independently witnessed and verified by up to seven separate parties providing robust assurance of compliance at the point of handover," said Graham Construction.
"Following completion of the handover process, GBHP has had no involvement in the management, operation, or maintenance of the hospital. GBHP has not been party to, nor involved in, any matters arising after handover, including the ongoing issues relating to water quality within the building."
