Compass Group holds a total of two weeks' food supply in the South at all times.
Interim chief executive Chris Fleming said the DHB had spoken to Compass after yesterday's earthquake and aftershocks.
''Compass hold a number of weeks' stock locally to ensure business continuity.
''If, in the future, there is any potential interruption to the food supply Compass will notify us immediately,'' Mr Fleming said in a statement.
The board did not respond to a request for further information.
In a statement, the Compass Group said the service had not been adversely affected, and it was working to ensure deliveries ''remain on track''.
The company had not activated its emergency contingency plan at this stage.
''We are working with the SDHB and our suppliers to ensure delivery times remain on track,'' the Auckland-based spokeswoman said.
''I can confirm that we do have two weeks of supply of food down there.''
State Highway 1 from Seddon to Cheviot remained closed because of slips, but the Picton to Blenheim/Seddon section had reopened, the New Zealand Transport Agency said in a statement yesterday afternoon.
Last year, in response to questions about the proposed outsourced service, Compass said it would truck frozen meals on wheels from the North Island, while parts of hospital patient meals would be trucked from other centres, including in the North Island.
An alternative route to Christchurch - from Picton through Murchison and the Lewis Pass - was reopened last night.
