Both terminals at Gatwick Airport are being affected by a water supply issue, with toilets reported to be out of order and restaurants closed.
In a statement on X, the airport in West Sussex apologised for the disruption, external and said a problem in the Horley area was affecting supplies and was under investigation.
Bottled water is being made available to passengers and staff and contingency measures have also been put in place, it said.
SES Water, which covers parts of Kent, Surrey and south London, as well as the airport, said it was working to restore normal service.
A spokesperson for the water company said: “Due to a number of complications caused by a power outage at our Bough Beech Water Treatment Works, some customers are experiencing low water pressure or a temporary loss of supply.
“We are working to overcome those complications and return the treatment works to supply as quickly as we can.”
She confirmed Gatwick Airport was affected, adding: “We are working with them while our teams work to restore normal service as quickly as possible.”
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