IN my hand was a bottle of birch water. Birch, the tree. But water, in a bottle. When I reached to pick it up my hand bypassed coconut and maple water, water supplemented with electrolytes and water boosted with yerba mate. I sipped my birch water and it was disgusting, and I disgusted myself for having spent £2 on it.

Cut to last week at the airport, going on a long haul flight. Aren't we always told that flying is dehydrating? Aren't we always told to drink plenty of water when we travel? Aren't boozed up passengers a perennial problem for airlines? So why am I being charged $7 for a small quantity of bottled water when I could buy the equivalent amount of beer for $2.99?

"It's because you need water but you want beer," says the man behind the counter. "They charge what they like when it's something you need."

It's not even mineral water, it's filtered tap. Council juice, in a plastic bottle. The worst airport price I've come across is when I was charged the equivalent of £12 for two litres of water.

But actually, while the luxury of flying is a privilege, why should access to water at airports be?

It's possible to take an empty bottle through security and fill it up on the other side, but that's a gamble because not all airports offer water fountains. In the UK, fewer than half of airports offer drinking water to passengers.

I object both on principle and common sense to buying bottled water. The UK's bottled water industry was worth £2.5 billion last year. That's bananas, or would be if bananas grew in our homes but we paid someone to peel them for us. We're paying £2bn a year buying three billion litres of something already readily available in our homes for a price 500 times cheaper.

We live in Scotland, guys. This stuff falls from the sky.

While my man in the Rhode Island duty free is correct in his ascertain that we need water, he's not quite right that we don't want it.

There is such a thing as a water sommelier. There is also a documentary about a water sommelier called There Is Such A Thing As A Water Sommelier. A man with a fancy palate making a living discerning the flavour variations of water. Water low in minerals, say, is described as having a "smooth mouth".

I drink about eight litres of water a day (yes, that's right; no, don't ask) and I can tell you this: water absolutely tastes very different depending on where you are and from where you source it. Is creating a tasting menu a worthy career choice? I'm afraid, it is not.

Remember that episode of Only Fools and Horses when Del Boy and Rodney bottle tap water in their flat and sell it as Peckham Spring? In 2004 we, the Brits, the sensible ones, saw off Coca-Cola's Dasani water after it was revealed to be filtered tap water from the mains supply in Sidcup, Kent.

Look now: one may purchase a bottle of Iceberg. This water is sourced from the Canadian Arctic ice shelf, frozen 10,000 years ago and waiting for its moment in the sun. Producers of the drink are not allowed to remove parts of the iceberg and so must wait for them to calve off naturally, net them like silver darlings and wait for them to melt.

The global bottled water market is expected to reach $280bn by 2020. This is capitalism at its very peak. Sell them something they already have.

That all, of course, is before the environmental impact is considered: it takes 162g of oil and seven litres of water to make a single one litre PET (polyethylene terephthalate) bottle, releasing 100g of carbon dioxide.

Something else I noticed at the other end of my long haul flight: in the US there were water bubblers everywhere. A quick bottle refill was easy: at museums, in shopping centres, on the street. I'd have to wrack my brain to think of a handy water fountain in Glasgow.

But in the Glasgow Fort branch of Pret recently I spotted a water tap. This week the company announced it will be fitting similar in other of its stores, selling reusable glass bottles customers can refill.

Pret's CEO, Clive Schlee, said: "The aim is to understand if customers will choose to refill a bottle rather than buying a new plastic one."

Here's hoping this is the start of a sea change (Yes, you can buy bottled sea water). We're embarrassing ourselves and destroying the environment.

Oh, common sense. If only we could bottle that and sell it.