Thousands of people in east London are still without running water on Wednesday morning after a burst pipe in Hackney Marshes triggered a major outage.
Thames Water has said the issue was first reported at roughly 6.30pm on Tuesday evening but said the wooded area where the pipe burst makes the issue difficult to solve.
The issues are affecting much of east London, and disruptions are expected to last late into Wednesday.
In a statement on Twitter, the company said: "We're aware customers in E6, E7, E10, E11, E12, E13, E15, E16 and E20 are experiencing no water/low pressure."
Later, it said: "Due to the size and scale of the burst, we do expect supplies to be interrupted for the next 24 hours."
On Tuesday night, it said it was "bringing tankers into the area to pump water back into the network".
Customers have been advised to continue to check the Thames Water website, and only phone if they need emergency support, due to the surge in calls.
Bottle water stations are being arranged for vulnerable customers and hospitals in east London for Wednesday morning as teams work through the night.
Explaining the scale of the crisis, the company said: "The burst is situated in a heavily wooded area in Hackney Marshes which makes the repair complex."
Many people living in east London shared pictures and video showing shoppers panic-buying bottled water.
In one clip from a branch of Tesco in Leytonstone posted on Twitter, shoppers can be seen carrying a number of large four-litre water bottles at a time, while a picture from the same account shows shelves completely bare.
A number of joke posts appeared on Twitter from people claiming to be selling water to residents in east London.
An ad which appeared on eBay claimed to be selling 1,400ml of "fresh tap water" to people in "Newham only" for £100 plus £3.70 postage.
Another Twitter user posted a picture of a small bag of water, writing: "Selling water £10 a gram in east London."
While one user said he could deliver a 500ml bottle of water for £10.99.
Fears are growing of another surge in coronavirus cases with people unable to wash their hands.
The issues have also affected people in Reading, Berkshire, where Thames Water was giving out bottled water.