The party won 11 of the contested seats, leaving it with 25 councillors overall on the authority.
Millions will vote in the local elections, including in Sussex, Surrey, and Tunbridge Wells, Kent.
The town is one of four areas of the country taking part in the early-voting trial.
Southern Water says the leak is not related to its infrastructure, but to nearby private land.
The pilot scheme allows people to vote early at dedicated hubs over the weekend before polling day.
A major gas mains replacement roadworks project is continuing as it is so far ahead of schedule
Dandara South East says the 520-home estate could be built on farmland near Paddock Wood.
