Why pay for water that comes out of your tap?

Who convinced you to pay for water that comes out of your tap?

Not a plumber. A marketing department.

For most of history, you only bought water if the well was bad, or you were abroad.

Then, in the late 1970s, a French spring water spends big in America. Glamorous adverts, a famous voice, and a little green bottle.

Water becomes a fashion accessory. And the giant drinks firms take notice.

Here's the trick. Some best-selling brands aren't spring water at all. They're filtered tap water.

In two thousand and four, Coca-Cola launched its Dasani water in Britain, sold as pure.

Then the papers found out where it came from. The mains supply, in Sidcup.

Weeks later, it was pulled from British shelves, after tests found too much of a chemical called bromate.

Meanwhile, British tap water is tested constantly, and costs a fraction of a penny a litre.

A bottle can cost hundreds of times more. For water you already pay for.

So when something you already have is sold back to you in plastic, ask who filled the bottle. Keep your nose to the wind.