It is thought a water pipe burst because of an electrical power surge which impacted the hospital. 

The boost in energy may have caused a knock-on surge in the hospital’s water pumps, flooding the pipes with too much water and causing one of them to burst. 

This led to the “spectacular” scenes in a corridor on the ground floor of the hospital, an NHS spokesman told The Telegraph, and a number of patients had to be evacuated from wards A5 and A6, which are used as general medical wards.

The water was clean, running water, and all patients were redistributed safely within the hospital, and by 2pm the water supply was largely back to normal.

Penny Emerit, chief executive, at Portsmouth Hospitals University NHS Trust, said: “We are continuing to run a major incident from the Queen Alexandra Hospital site following a significant water leak early this morning. 

“Work has been ongoing to identify the source of the leak and we are now testing the water supply to ensure that the water supply is resilient across the site. 

“Our priority is to ensure that we can safely care for our patients currently with us and reduce the number of people onsite.

“We have taken the decision to cancel all of today’s remaining outpatients and elective procedures. 

“However, maternity appointments will go ahead and some outpatients clinics are contacting patients directly if their appointment can go ahead. 

“We are also running lifesaving surgery, renal dialysis, chemotherapy and radiotherapy. Our Emergency department remains open for the most serious life-threatening emergencies, but please use alternative services where possible.

“I would like to take this opportunity to thank colleagues across the Trust who have responded brilliantly to this situation. 

“I’d also like to thank partners from across Hampshire and the Isle of Wight and the region and our local community for their ongoing support and assistance.”

Two fire crews were sent to the hospital from Cosham Fire Station at 5.46am to help with the issue. 

The hospital added that virtual appointments will still continue as planned, and patients who had their face-to-face slots cancelled may be contacted to be offered a video call instead. 

Maternity outpatient appointments will also continue as usual, the hospital added.

The incident came at a time when 8 per cent of the Portsmouth Hospitals NHS Trust’s workforce was absent, equating to 627 members of staff. 

According to latest figures, there are 65 patients in the trust’s care with Covid, and 19 of those patients are in intensive care. 

Hampshire and Isle of Wight Fire and Rescue Service said: “Cosham firefighters were called at 5:46am this morning to assist with a major incident at QA Hospital. 

“Crews used a pump to remove water and worked alongside onsite staff to prevent further flooding before leaving the scene at 7:45am. 

“Officers continue to liaise with partners to ascertain how we can assist.” 

Anybody concerned about appointments are asked to check the trust’s social media platforms and website.