Admits error with Macquarie Telecom data centre.

Sydney Water has admitted its maintenance crew shut off water supplies to Macquarie Telecom's data centre on Friday night by mistake, leading to an outage at the facility.

The utility said a crew fixed a leaking pipe connecting a shop to the mains in Pitt Street at the south end of the CBD.

"The crew shut off the water to the business at 9pm Friday but inadvertently shut off water supplying Macquarie Telecom's data centre," the utility's spokeswoman said.

She confirmed Macquarie's account that it notified the utility of the problem on Saturday morning.

"A crew returned to the site at 9am Saturday to restore water services to the Telecom building," she said.

"Sydney Water apologises for any inconvenience caused by the water being shut off."

It affected air conditioning in the managed services area, leading to the use of redundant systems and a forced shutdown of customer equipment for about two hours.

Macquarie Telecom declined to comment on Sydney Water's admission.