Thousands of homes are without water in the Reading area.
Thames Water is trying reconnect residents and has started to stockpile bottle water to distribute to those affected.
A campus at Reading University has been closed after it was left without water because of a broken pump.
The University has released a statement explaining the university's closure after a fault in the wider network in the Lower Earley area.
The Deputy Vice-Chancellor, Professor Tony Downe, said: “Thames Water says its engineers are working to restore supplies as quickly as possible, but it can currently give no clear estimate as to when it will be fully restored.
"We have considered our options carefully. There are only limited tank supplies in most of the University's buildings. Without water for sanitation or drinking, a decision has been taken to close Whiteknights campus with immediate effect."
Thames Water have confirmed 20,000 homes are without water in Reading this morning.
“We’re really sorry to our customers in parts of Reading who are without water. The problem is with a pump that pushes water through our network and engineers are on site now investigating what has happened.”
Thames Water is apologising to customers in the Earley area of Reading. The supply problems are due to a fault in the water network.
The water firm says engineers are working to restore supplies as quickly as possible.
Sorry to our customers in Reading who are without water. Engineers are working on this - we'll update as soon as we have more info.
Thames Water have said that customers in Berkshire affected by poor water quality, will receive a £100 goodwill cheque.
Around 1500 homes are thought to have been affected in the Streatley, Ashampstead, Upper Basildon areas and a small part of Pangbourne.
Engineers are now confident that the water is safe to drink again
They spent yesterday visiting properties in the area collecting water samples and worked into the early hours of Sunday morning sending them for quality testing.
Affected customers will be receiving letters today confirming that they can now drink the water.