About 4000 people will have their medical appointments postponed after a flood in the Christchurch Outpatients building on Friday.

Photo: Supplied

The building will remain closed until next Monday, after steam from a burst heating pipe activated the fire sprinkler system, causing significant damage to walls, floors and ceilings.

The Canterbury District Health Board said a new valve for the heating pipe was needed and all pipework would need a hydraulic test before it was back in operation again.

The health board is postponing about 700 appointments each day and contacting any affected outpatients by phone or text.

Urgent appointments are being moved to alternative locations.