Homes in the Friston and East Dean have been left without water overnight after a serious burst on the area's water main.
Steve Andrews, incident manager at South East Water, said: “The repair team worked through the night to remove the damaged pipe in what continues to be an extremely difficult repair. Temporary repairs have not been successful and we now need to manufacture a specialist part to replace the broken 21 inch valve.
“Around 400 customers continue to be without water or are experiencing low pressure and we anticipate that they will be without supplies for most of the day, due to the seriousness of this incident.
“Bottled water has been delivered to vulnerable customers on our Priority Services Register and further supplies of bottled water can be found at East Dean Village Hall, Village Hall Lane, BN20 ODL.
“We would like to apologise to our customers for any inconvenience this emergency has caused, but hope our customers understand that we are taking all necessary steps to restore supplies as soon as possible.
"Residents can register for future updates by email or text using the In Your Area map on our website, southeastwater.co.uk, or follow us on Facebook and Twitter for regular updates on our current supply problems. For water emergencies, we are available 24/7 on 0333 000 0365."
South East Water is handing out bottled water in Jevington, as a result of the serious pipe burst.
Mr MacIntyre said: “Around 400 South East Water customers continue to be without water or are experiencing low pressure. The local water supply was turned off at 6pm yesterday (Wednesday 31 May) to enable our technicians to carry out the repair, and we anticipate that they will be without supplies for most of the day, due to the seriousness of this incident.
“Our specialist team is still working hard on the complex repairs to remove the damaged valve which has given faultless service since the 1930s when it was installed and cased in concrete to prevent movement.
“A bespoke part is in the process of being manufactured to replace the broken valve, which connects two 21 inch water mains supplying water from Friston Water Treatment Works to customers in Friston and East Dean.
“Bottled water station are now operating from Eight Bells pub, Jevington Road, BN26 5QB and at East Dean Village Hall, Village Hall Lane, BN20 ODL. Bottled water has been delivered to vulnerable customers on our Priority Services Register."