NEW YORK • Most kids do not drink enough water, according to a 2015 study in the American Journal Of Public Health.
They are so accustomed to sugary drinks, they find clear, unsweetened liquids unpalatable.
Enter a steady stream of start-ups and long-time industry players which hope to change that mindset.
Mr Gerry Khermouch, founder of industry publication Beverage Business Insights, said: "They've tried every permutation of recipe - unsweetened, juice-sweetened, naturally sweetened - and almost all inevitably fail."
New companies such as Rethink Brands and Hello Beverages are trying to reverse the trend with sugar-free, zero-calorie beverages that are essentially flavoured water in a box.
Mainstream brands like Capri Sun and Mott's have introduced better-for-you options, while Coca-Cola Co's Honest Kids drinks are available in McDonald's Happy Meals.
The beverage makers want to distance themselves from longstanding accusations that sweetened juice boxes are no better for kids than soda pop, which contributes to obesity.
To sell to mum and dad, more than three-quarters of new kids' juices touted their lower sugar content last year, according to consumer researcher Mintel, up from just one-third in 2004.
But kids love sweet drinks. And they can be fickle.
Even Kraft Heinz's Capri Sun, the long-time segment leader, has gone through three straight years of market-share decline, according to data tracker Euromonitor, even with the introduction of Fruit Refreshers and Fruit & Veggie Blends with no added sugar.
The broader industry's sales volumes in America have fallen to half of what they were in 2007.
A cautionary tale is Wat-aah, which debuted in 2008 with what its makers called "natural fruit essences". The company tried to "make water cool" by aligning with pop stars like the Jonas Brothers and Ariana Grande.
Wat-aah generated a lot of chatter on social media, but when the buzz died down, so did sales.
A rare success is Honest Kids, an organic offshoot of Honest Tea that hit the market in 2007 with less than half the sugar of most juice boxes at the time. Sales of Honest Kids, acquired by Coca-Cola in 2011, now eclipse those for Honest Tea.
The brand has grown by pushing into fast-food chains like Wendy's, Subway and McDonald's.
"It's very easy to say kids should drink more water," said Honest co-founder Seth Goldman. "But kids need some flavour."
Still, it can be hard to count on kids for brand loyalty.
Mr Mike Weinstein, former chief executive of Snapple Beverage Group who now runs his own consulting firm, fields calls all the time from entrepreneurial mums who want to get into the business.
His advice: "I tell them to save their money."