Innocent Drinks' water brand This Water will become an £80m brand within three years, the company is predicting, thanks to new formats, international expansion and the addition of vitamins to give the drink a functional edge.

The brand relaunched from Innocent Juicy Water to This Water 12 months ago, when it was worth £8m. It is expected to more than double in value this year to £20m, boosted by its first above-the-line marketing campaign in June, said This Water MD Douglas Lamont.

"We overcame the confusion about whether this was a smoothie, a watered down version or something totally different," he said. "We expect to double the size of the brand in every year of our three-year strategy. The market backed the rebrand as they saw we were growing and investing in the brand independent of Innocent. We can now say it's been a massive success."

In the past month distribution has been boosted by a roll-out through Boots, an increase from 10 Tesco stores to more than 200 and entry into BP last week.

The business is working on extending its shelf-life with a view to opening up the European export market and targeting UK wholesalers. "We need to double our two-month shelf-life, but without affecting taste or quality," said Lamont. "We should complete this by the end of the year."

New sizes, such as larger take-home bottles and smaller formats, are all being considered for 2009 in an effort to tap into more occasions. "At the moment it's a grab-and-go format, but it could be a drink that's kept in the fridge or taken to parties," he said.

Creating functional variants will be a key focus for 2009, with trials currently under way to add antioxidants and vitamins .

The company is doubling its marketing spend to £1m this year, including its first press and poster campaign.

This Water currently accounts for about 10% of Innocent's UK sales, but that proportion will increase significantly, added Lamont, as the market had far more growth potential than smoothies.