Justin Timberlake just gave a huge boost to a brand that's becoming a threat to Coke and Pepsi

Justin Timberlake is about to give a huge boost to Bai Brands, one of the fastest-growing flavored water companies in the US.

Timberlake is joining the Bai team as an investor and the brand's first chief flavor officer, the company announced Thursday.

He will also star as the face of the brand in a $100 million marketing campaign that Bai is launching next year, the company's founder and CEO Ben Weiss told Business Insider.

It will be Bai's biggest marketing campaign since its founding in 2009.

Company sales have grown 150% since launching its first national marketing campaign last year. Sales in 2015 totaled $120 million and this year they are on track to reach $300 million.

As chief flavor officer, Timberlake will be intimately involved with the executive team at Bai's Trenton, New Jersey headquarters, Weiss said.

"He'll be involved in everything from flavor innovation and product launches to marketing and digital content," Weiss said. "We will see a lot of him. His fingerprints are going to be on this brand."

Bai Brands makes drinks called Bai, Bai Bubbles, and Antiwater. The first two drinks offer fruit flavors and antioxidants with no artificial sweeteners and just 5 calories and 1 gram of sugar per serving. Antiwater has "antioxidants in the form of a super-purified bottled water," the company says.

Flavored water brands like Bai have become a major threat to companies like Coke and Pepsi, which have seen soda sales plunge over the last decade as people opt for healthier drinks instead.

Bai's relationship with Timberlake was forged about five months ago, when a common friend put Weiss in contact with the the actor and musician. Weiss said he traveled to Los Angeles to meet with Timberlake and they talked about the possibility of a partnership.

Timberlake was a huge fan of Bai at the time and stockpiled the drink where his wife, actress Jessica Biel, couldn't find it, according to Weiss.

"He said he found himself drinking it and storing it away from his wife in a secret little refrigerator," Weiss said. "He was very passionate about it."

About two months ago, Timberlake visited Bai's New Jersey headquarters, where he met with the company's executive team and recorded a series of videos that were shared internally with Bai's employees.

"I've been a fan of Bai for a long time and when I met Ben and his team, it became clear that I should be involved with this brand," Timberlake said in a statement. "As a father and someone who is cautious about what my family and I consume, I love what Bai stands for. This partnership was created from a shared desire to help people put better ingredients in their bodies without sacrificing taste."