Wellington Hospital's emergency department has close to full capacity for months on end, with one patient describing it as "busier than an airport terminal".
Hutt Valley and Capital & Coast DHB has reported the ED has been full for more than two thirds of each day since March, resulting in higher than usual wait times to see a doctor.
The health board also said there had been a very high number of children presenting with respiratory illnesses, with around 100 admitted to Wellington regional hospital in the past four weeks.
A Wellington resident admitted to the emergency department on Wednesday told the Herald he had never seen the hospital so full.
"I heard wait times were in excess of six and a half to seven hours to get [seen]."
He said he was seen immediately, because he was admitted via ambulance, but waited more than 12 hours after being seen to be put on a ward.
However, he emphasised hospital staff were working extremely hard, and the care he received had been "second to none".
"When they came around to apologise for the wait time, they said every hospital room was full and it was basically a one-out, one-in basis they were operating on," he said.
He had also noticed a high number of children and babies coming through, he said.
Hutt Valley and Capital & Coast DHB Director of Provider Services Joy Farley said patient numbers at Wellington Regional Hospital continued to be high.
"Te Pae Tiaki Wellington ED is seeing high volumes of presentations with increasing acuity and, since March, ED has been full for more than two-thirds of each day – regularly exceeding well over 100 per cent occupancy."
Farley said people were assessed by a nurse upon arrival to ED and prioritised for treatment based on their level of need.
"This, along with high demand, mean that patients who are assessed with non-urgent needs are experiencing – sometimes significantly – longer wait times to see a doctor.
"Anyone who requires urgent or emergency care receives it without delay."
Patients were also remaining in ED longer after seeing a doctor, due to high demand for beds across the hospital, Farley said.
"It is not possible to say how long these patients wait as this depends on the ward they are being admitted to, their level of need, and a range of other factors related to their care."
Yesterday Farley said the DHBs were looking into increasing capacity at the region's three hospitals due to the continued high levels of occupancy, requiring investment in the coming year.
"These investments will be in line with master site planning and will be undertaken as soon as possible," Farley said.
"As we head into winter – especially as we are at alert level 1 – we strongly encourage people to maintain good hand hygiene, stay home from work or school if they have cold or flu symptoms, and to contact Healthline on 0800 358 5453 or their GP for advice."