The threat of homelessness is keeping people in hospital longer than they need to be, mental health services in Christchurch say.
At one Canterbury District Health Board facility, five people no longer need the level of care they're getting but there was nowhere else for them to go.
The DHB's general manager of mental health Toni Gutschlag said another 15 patients who are not ready to be discharged are homeless, and will face the same situation.
People have not been turned away, but Ms Gutschlag said this could could happen if the problem was not addressed.
She said the shortage of social and affordable housing meant people were staying longer than they needed to and that meant those beds were not available to others who might need them.
"We have had a situation where we had all 64 beds full and a total of 87 people under care, so those people were staying in other in-patient wards or in other arrangements in respite in community service."
Christchurch City Council is the second largest provider of social housing in the country.
About 97 percent of the council's social housing units were damaged in the earthquakes and are in need of repairs or replacement.
Councillor Vicki Buck said the housing problem was not only a concern in the mental health sector. The the council can not be the only answer and a range of organisations needed to be working together, she said.
She said the housing committee was in the process of compiling a report on social housing to put before council by early September.