Ermha chief executive Peter Waters warned that about 12,000 people with a severe mental illness were missing out on help from the region's main non-clinical service due to under-funding.

"The ramification is that the community service system is under siege," he said. "Only people having a mental health crisis get the service they desperately need.

"In a way, we are training people to have a crisis to get help. The irony is the research shows the earlier we intervene the better the prognosis for that person."

In the previous financial year, Ermha, the south-east's main community mental-health service, got a $3.1 million revenue injection, taking its funding to $12.2 million from state and federal sources.

But this increase was "relatively flat" compared with the funding for hospital-based services and the region's sharp population growth, Mr Waters said.

Ermha provides services such as outreach, respite and residential support to about 1200 people with severe mental illness and their carers in the region each year.

Without the right support at the right time, people with a severe mental illness were at greater risk of relapsing and getting caught up in a cycle of going in and out of hospital, Mr Waters said.

"The bulk of a person's recovery occurs in the community-based services, not in clinical in-patient settings." .

Sharon Haliman became her brother Tim's full-time carer to get him out of a hospital mental health ward. Three months later, depressed and desperate for support, she was close to suicide.

"When I picked up Tim from a psychiatrist at the hospital, I wasn't told about carer support or respite," she said.

"I begged them to put a plan in place, like what do I do if he goes backwards. I was depressed because I didn't know how to deal with the issues Tim had."

It took a call to a Lifeline operator for Ms Haliman to find out about community-based support services.