The operation to quench the fire at the Buncefield oil terminal in Hertfordshire in southeast England has been suspended.
Hertfordshire Chief Fire Officer Roy Wilsher said the decision was taken due to fears about the content of one of the tanks which is still ablaze.
For most of the day over 100 firefighters have been attempting to douse the fire, which began after a series of explosions at the oil depot.
32,000 litres of water mixed with foam were being pumped every minute to try to put out the flames. The plan was to deny the fire oxygen and to cool the oil.
Crews had put out fires in 12 of about 20 blazing fuel tanks before the operation was suspended.
A temporary road has had to be built to enable crews to take equipment, including six high volume pumps and a crane, to the water supply.
42 people were injured in the depot blasts, one seriously. 2,000 people living near the site have had to leave their homes.
Police believe the explosions were accidental but they do not yet know the cause.
Some flights into Heathrow Airport were forced to delay landing because of smoke. Luton Airport was said to be operating as normal.
More than 70 schools in the area are closed so that children can be kept indoors.
Scientists are to assess the damage to the environment caused by the smoke cloud which is visible from space.
