The burst pipe in Keeper’s Wood, near the A21, needed to be removed and replaced.
Because of its “difficult” location, director Tim McMahon said the company had to fell 50 trees in order to get to it.
“This is, by far, the most difficult location I’ve ever seen,” he told Radio Sussex.
Falling on the bank holiday weekend, the outage will impact events such as the annual four-day Jack in the Green Festival and the May Day Bike Run, which usually see thousands of people visit Hastings.
