The water challenge on TikTok refers to two different challenges that have been trending on the platform. The first one is a dance challenge called the "Water" challenge, which is a mix of twerking and belly dancing. The second one is the 30-day gallon water challenge, which involves drinking a gallon of water every day for 30 days. The challenge has been popular on TikTok, with many users claiming that it makes their skin glow, boosts their energy, and helps with weight loss. However, experts warn that drinking too much water can be dangerous and lead to water intoxication, which can cause seizures, brain damage, and even death. Therefore, it is important to drink water in moderation and consult a doctor before starting any new health challenge.