About 150 staff had to abandon their desks when a pipe burst at the council’s administrative headquarters in Northgate House, Halifax, this week.
Water poured though four floors of the building bringing down ceiling tiles, destroying electrical equipment and leaving piles of sodden paperwork.
Some staff had to be moved to temporary office accommodation elsewhere in town. The cost of the damage and essential repairs is still being assessed.
It is thought that the pipe probably burst on Sunday and it wasn’t spotted until staff turned up for work on Monday morning.
The reception area was unaffected but the incident severely disrupted some internal and back office services, said a council spokesman.
Councillors agreed last year to close Northgate House and reorganise accommodation for office staff who are housed in 11 separate buildings.
Northgate House was built in 1982/3 at a cost of £3.8 million. It is due to be sold in a year or two to create space for retail development.