Financial Conduct Authority staff were sent home on Wednesday from the regulator’s headquarters on the edge of the Queen Elizabeth Olympic Park after reports there was no water in the building’s toilets.
The FCA began relocating 3,000 staff to the new base at 12 Endeavour Square from Canary Wharf in the summer.
The move to the new 425,000sq ft building is costing £60m.
A spokesman for the FCA said: “The FCA building at 12 Endeavour Square is currently experiencing an issue with the water supply. As a result the building was closed [yesterday] afternoon and staff were sent home.
“We have instigated our business continuity plans so our critical functions, including the contact centre, continue to operate and staff are able to access our IT systems. We have raised the issue with the landlord and insisted that it is fixed as a matter of urgency.”