Gatwick Airport says its water supply has returned after passengers faced long queues for toilets and closed restaurants and bars after a major supply outage.
Both terminals at the UK's second busiest airport lost running water on Sunday morning after a power failure at a treatment works that serves the area.
People told the BBC of confusion and frustration as all bars and restaurants were shut, some were left with nowhere to sit and waits built up outside toilets.
SES Water, the company that supplies the airport, said earlier the power outage was fixed, with Gatwick reporting on Sunday night that water had returned to "the vast majority of the London Gatwick campus".
The water company, which also supplies parts of Kent, Surrey and south London, said complications caused by a power outage at Bough Beech treatment works meant some customers had experienced low water pressure or a temporary loss of supply.
A spokesperson had earlier confirmed that Gatwick Airport was affected.
On Sunday afternoon, SES Water said its treatment works were back up and running, but later added it would take time for the network to fully return to normal as it had been "a highly unusual and complex issue".
"We want to reiterate that our teams are working as quickly as they possibly can and we are grateful for everyone's patience," the spokesperson added.
Gatwick apologised and said staff had been handing out bottled water.
A spokesperson added: "Our staff are on hand to support passengers and provide assistance where needed, some restaurant partners have opened to provide additional seating."
Gatwick said additional teams had been deployed across both terminals to support passengers.
The airport added there had been no flight cancellations as a result of the supply issues and that it was working closely with SES Water to minimise the impact.
"Our teams are working hard to reopen toilets and other facilities as quickly and safely as possible," a spokesperson said.