So, there we were, flying along through France when the senior cabin crew member noticed that her glass of water had a head on it. Now, it wasn't a full blown Bavarian beer froth, or a rich creamy top of northern ale, but it was definately a head of some sort.

She filled a few more glasses, and as she did so, my dependable and highly competent (not to mention stunningly gorgeous) senior crew member noticed the water slowly turning a pale shade of blue. Now, a little technical stuff here: whenever you buy a coffee or other hot drink on board a plane, the water is drawn from the aircraft's potable water supply. This is a large tank of water which sits somewhere in the respective aircraft's structure and is replenished by a truck during turn-arounds. Goodness knows where the truck gets the water, but it's safe to assume it isn't Perrier. This water can be supplied cold (more fool you) or heated, though not necessarily boiled.

By the time the blonde haired, blue eyed Swedish senior (and I'm not making this up) had filled a few glasses, the water was looking more like a glass of washing up liquid than a glass of nature's finest. This is the stuff we had been drinking all day; this was the stuff that was sitting in my cup holder as Helga (nother  real name) entrered the flight deck holding her latest laboratory sample.

Now. You know how you can feel instantly better whenever a 'medical person' persuades you that this herbal/homeopathic/natural/Chinese/ancient remedy will cure you of your psychological illness? (No, me neither) Well, the opposite is true. We all started to feel quite unwell. And then it got worse.

After discussing the discovery with our company, it transpires that there had been a mix up with the ground staff at Nice airport in the south of France. A little more technical stuff: the point where the water truck connects to the Airbus aircraft is next to the recepticle which allows the honey wagon to flush through the toilet system. The honey wagon is a euphemism for truck which drains the crap and weefrom the aircraft's waste system. To do this it pumps a blue liquid into the pipes by connecting a hose to the appropriate fitting next to the identical fitting for the fresh (and laughably drinkable) water supply. These French aircraft designers really though about this one.

So what was actually in Helga's glass, and what we'd been drinking all day, was in fact some blue stuff which was used to flush out the bloody toilets! Perrier, it most certainly wasn't!

And airlines actually charge you for this stuff. Next time you order a coffee on board a plane, makes sure you it's not a cappuccino!