Water has been returned to most homes after a "major burst" in a pipe affected large parts of east London, Thames Water has said.
People in nine postcodes had no water or low pressure after a main ruptured at Hackney Marshes on Tuesday.
The utility company said water was being routed into the area from other parts of the network while engineers work to repair the pipe.
As a result water pressures were increasing in the area, the firm added.
The 42in (106cm) diameter pipe burst in a woodland area on Hackney Marshes, causing problems in surrounding areas including Barking, Forest Gate, Leytonstone, Ilford, Plaistow and Stratford.
Thames Water had received about 1,000 calls by Tuesday evening from people who had no water or low pressure.
People also reported panic buying of bottled water with shelves cleared in some local shops.
The damaged main created a flood covering an area of 300m by 300m to a depth of 1m in Hackney Marshes, which had made work to repair it "really challenging", Thames Water said.
The company said it had used to tankers to pump all the water out of the woodland before isolating the pipe and cutting out a 6m section of it.
"We're continuing to carry out work across the local area to get things back to normal as soon as we can," they said.
The firm added that anyone who was still experiencing no water or low water pressure should contact them.