Transport for London has insisted a fire hydrant was to blame for a plume of water seen in south London this morning.
Social media was full of pictures of the incident at Elephant & Castle, which was likened to the fountain on Lake Geneva.
Thames Water said it attended the scene and replaced a cap on a fire hydrant, which it said had been “knocked off” by workers.
But a spokesman for TfL, which is carrying out a £25M overhaul of the Elephant & Castle Northern Roundabout, said a fire hydrant had failed.
“Workers were laying paving slabs and turned a valve on the hydrant to access water for the job when the hydrant failed,” he said.
“When opening the cap to see if it was live, the cap blew off. It had not been closed due to a faulty valve and was running off a high pressure main.
“If the hydrant had been damaged, it was not done by us or our contractors.”
The TfL spokesman added that Thames Water attended the scene quickly and fixed the hydrant. He said the incident didn’t cause any delays to the roundabout project.