Nearly 8,000 people have pledged not to drink alcohol in September as part of an annual campaign, which began 10 years ago.
A social media event has attracted 7,000 people since being launched a week ago, all promising to remain sober during September.
The tradition began to attract popularity in 2004, when more than 200 participated and a student-run NGO was set up. The drive moved to Facebook in 2010, with 1,000 people taking part, and it has mushroomed ever since.
Last year around 2,500 took part.