I’m from the United States, and it’s hard to say that there is.
EDM festivals here in the US are either 18+ or 21+. The 21+ older shows usually involve more people using drugs/alcohol, and the 18+ shows probably would have less.
There are a few that are not entirely crazed with drugs and alcohol.
Coachella would be one of them. Coachella is a very large and open music festival (not just EDM). Coachella is of all ages, and it’s considered one of the most popular music festivals in America. Tomorrowland in comparison is not.
Again, it’s really hard to say whether or not there is a festival that is drug-free because even if the festival strictly prohibits the use of drugs during or before the show, there will always be those who would go out of their way to bring it in. Ultra, Tomorrowland, EDC, all of these are more than likely to have people not sober during the festival, I assure you that.