More than two and a half million Brits struggle to recall the last time they had a plain glass of water. Research has revealed almost half depend on cups of tea to maintain hydration, with a third relying on coffee or fizzy drinks. Baby boomers are twice as likely as  Gen Z to depend on tea for their fluid consumption. Meanwhile, women are more prone than men to fail to consume sufficient water. The survey based on 2,000 adults found only 17 per cent are drinking adequate water, based on NHS guidance which recommends up to eight glasses a day.

What's more, one in ten parents polled don't believe their children drink enough each day. The study, which also surveyed 837 teenagers, revealed 15 per cent of them consume plain water only a few times a week at most, leaving many parents concerned about their intake and three quarters having to 'force' their children to stay hydrated.

One mum, Kelly Mulligan, 53, says her son, Max who is nine, hasn't had a glass of plain water since he was four years old. The youngster would rather drink apple juice, which Kelly dilutes with water to keep his sugar content down.

"Max has never liked plain water he says there's no flavour," she said.

"I don't drink plain water either. I can only drink carbonated water or tea."

Kelly, from Brighton, who runs her own cleaning business, explained: "Max will take little sips of water if he needs to, but he's always thirsty and says plain water doesn't quench his thirst."

Max must bring a water bottle to school as no other beverages are permitted, though Kelly said she remains uncertain about how much he actually drinks.

"He's healthy and happy, so I have no concerns. He has a varied diet and keeps active. It isn't like he's drinking no liquids at all. The diluted apple juice is a middle ground which helps keep my concerns for his teeth a bay," she said.

The study, commissioned by hydration beverage Más+ by Messi, which champions proper hydration to help Britons perform at their peak, revealed that 34 per cent of teenagers aged 13-17 favour alternative drinks over water, whilst 26 per cent simply 'forget' to drink it.

Additionally, 29 per cent of adults believed tea, coffee and fizzy beverages were equally effective as water for maintaining hydration.

Nevertheless, 17 per cent regularly experience symptoms they believe stem from dehydration, such as headaches or fatigue.

Merely 12 per cent actively monitor their water intake, with 60 per cent making no effort whatsoever – whilst the remainder try to maintain mental records of their consumption.

Sophie Van Ettinger, global VP Más+ by Messi, said: "It's alarming the number of people who are not aware they are dehydrated daily and will often go through days experiencing a lack of energy or headaches, not realising a simple glass of water or even a hydration drink is the solution."

Leo Messi, co-founder for the drink, added: "As an athlete, I know the importance of hydration for peak performance."