Opposition Leader Jeremy Hanson says the incident shows that the money spent on furniture should have been used for other services.

But the government has defended the expenditure, saying the incident highlighted the need for extra heavy furniture at the unit.

A contract for the custom-made furniture shows the tables were purchased as part of a $370,000 joinery package.

The ACT government spent almost $100,000 on three tables for the reception and dining areas.

The tables were purchased as part of a $370,260 contract with Capital Veneering that also included the fitout of the unit's reception area and other furniture items.

ACT Health and Chief Minister Katy Gallagher defended the purchase of the tables this week, arguing the custom-made, solid spotted gum furniture was necessary to ensure the safety of patients and staff at the unit. The items also lifted the standard of living for patients there.

But one of the tables in the high dependency unit was damaged after a distressed patient attempted to tip it over. The table was too heavy and the incident only caused damage to the table leg.

Soft-cushioned furniture was used as a substitute while the table was sent away for repairs.

The floor also had to be repaired because the table was anchored to it.

Mr Hanson said family members of patients had raised concerns that the money spent on the tables could have been used for community mental health services.

"They've spent $30,000 for a table that was robust enough and it broke," he said.

"I think it's extraordinary that the government spent $30,000 and Katy Gallagher said that was so it was robust enough and it broke shortly after it was installed.

"You've got family members raising very legitimate concerns that money has apparently been wasted on tables that could have been spent on community mental health services."