The five-piece have decided that since Sarah can no longer drink alcohol to celebrate their shows, they will all abstain for the duration of the tour, which will see them travel the country from Cheryl's hometown in Newcastle through to Nicola's native Liverpool.
Sarah has struggled with her problems since she parted from her fiancé Tom Crane in 2011, and has since received help to tackle her alcohol problems and depression.
The Band performing at the Brit Awards last month
A source told the Sun: "The girls have decided to ban alcohol altogether in support of Sarah. She's still dealing with her alcohol problem two years on – and they've decided to ban it out of respect for her. It’s only fair, they don't want her falling off the wagon and going back to how she was after she split from Tom."
The source added that the rule even applied to all staff and the backing dancers on the tour, so if they want to enjoy a few drinks after the show they have to leave the arena first as the area around the dressing rooms will be completely dry.
The girls could also be hoping the ban will help them to be on tip-top form every night, as there have been plenty of rumours about that the shows will mark the end of their time together as a group.