It's the key to life on Earth, the most essential commodity on the planet, but most of the water we actually consume is just, well, a little bit boring. At least that seems to be the feeling behind the current trend for new twists on the universal solvent.
For Tony Conigliaro – an experimental mixologist and one of the few barmen whose name is known outside of that tightly knit fraternity – the creation of a hay-and-grass-infused water was prompted by a dearth of suitable non-alcoholic accompaniments to food.
"There are people out there who can't drink or won't drink," he says. "For them, what's on offer [in restaurants] can be extremely uninspiring. And it definitely doesn't go with the food."
At Grain Store, the new, trendily wholesome restaurant in London's King's Cross, Conigliaro decided to complement the food menu with a subtly flavoured water. The key ingredient is a water-based hay essence (a hydrosol) that is made using an alembic still affectionately called Maggie – the Copper Lady.
A mixture of water and hay is heated in the still, using a normal kitchen hob. This produces a concentrated vapour that is condensed, cooled and then added sparingly to filtered water – one gram is enough to flavour two litres of water.
The end result is unusual, to say the least. It's perfectly clear, but has a straw-like bouquet that unexpectedly makes its way up and into your nostrils long before your mouth gets to the rim of the glass. The taste, once it arrives, is savoury, lingering, and rather pleasant.
"But it's not just about a flavour," says Conigliaro. "It's about an effect and getting these subtle tannins in the water. They shrink the protein chains in your saliva, your brain kicks in and tells you to produce more saliva. And fresher saliva means that you can taste food better."
It all sounds very scientific, but for £4 a glass, does it represent value for money? "I think it does. It gives you another option. Drinking just water all the way through a meal feels like I'm diluting what I'm putting in my mouth, as though I'm washing away all those nice flavours."
But glasses of water have been known to change hands for far more than £4. In 2007, Claridge's introduced a water menu to rival some restaurants' wine lists, with bottles priced up to £50 per litre. The menu didn't last long and was discontinued, apparently, because of a drive to be "more environmentally conscientious".
Such concerns haven't deterred the Pass restaurant at the South Lodge hotel in Sussex from accruing a selection of 28 mineral waters from 14 countries. The Michelin-starred eatery offers tastings and advice on how to pair different waters with dishes on its menu. For example, a salty, naturally carbonated water such as Vichy Catalan has proved extremely popular with diners, but must be handled with care, according to restaurant manager Tommaso de Christofaro. Much better to match it with a robust red meat dish than risk it overpowering something more subtle, such as fish.
The Pass has made a deliberate decision to keep its water menu "accessible" and so prices range from £5 to £7 per bottle. That's more modest than its pre-recessionary antecedent at Claridge's, but it does mean that it must be content to do without idiosyncratic offerings such as Iceberg Water.
A bottle of this stuff retails for around £13, but for that price you get what the company claims is "the purest water on Earth", made from icebergs that were formed by snowfall that settled in Greenland 12,000 years ago. This means that, in terms of mineral content and quantity of "total dissolved solids" (TDS), it is many times purer than most of the more familiar brand names. In every litre of Iceberg Water there is the equivalent of 9 milligrams TDS, whereas Evian, for example, has 357 milligrams TDS per litre.
As part of a natural, annual process (albeit one that may be accelerated by climate change), about 1,500 icebergs detach from the Canadian Arctic ice shelf each summer and, over six years or so, float down towards the coast of Newfoundland in Canada.
A quite extraordinary video on the Iceberg Water website shows how the company "harvests" about four of these icebergs per year to make 75,000 to 100,000 litres of bottled water. (Highland Spring sold 2,000 times this amount in the UK alone last year, leading a domestic market that is worth £1.5bn.)
In scenes reminiscent of the BBC's 1957 April Fool's spaghetti farming hoax, a Canadian sea captain whips out a rifle, fires at a floating iceberg and proceeds to instruct his crew to use a net to haul the detached shard onto their boat. It's then melted and bottled in Newfoundland before being distributed all over the world.
I am assured by the company's founder that this is genuine, but can't help but wonder whether it's worth all the bother. Could most of us mere mortals really tell the difference between something like this and tap water? "It's like comparing a Kobe steak with a beef burger, says Michael Tanousis, the MD of Aqua Amore, the company that supplies the widest range of waters in the UK. "One is natural, one is a processed product, so it's not a proper comparison."
Still, when I do compare Iceberg Water and others (including a mineral water by the fashion house Armani) to tap water in my own taste test, I convince myself that there is a perceptible difference. Compared with the inert, light, clear Iceberg Water and the softly nuanced flavours of the others, tap water tastes almost dirty, and feels as though it has some kind of slick running through it. And is that chlorine I can smell? Having tasted the good stuff, perhaps I'll never be able to go back? But then I remember, tap water costs 0.1p per litre.
A sophisticated palette is not required, however, to discern the flavours of Halen Mon's smoked water. Intended for use in cooking and in cocktails, it has attracted the attention of Heston Blumenthal. A 150ml resealable pack costs £2.75, which may sound expensive, but it's highly potent and is not intended to be drunk neat. It adds an extra, unusual element to a long drink or cocktail such as vodka and apple juice, and a little bit really does go a long way. When you think about it in those terms, it's actually pretty decent value – a drop in the ocean.