Water is an essential ingredient in any spirit, but that doesn't mean a special water source makes a better spirit.

Most of the liquid in a bottle of gin or vodka is water.  The bottle even tells you that with a clearly visible ABV statement.  A bottle of supermarket gin at 37.5% is 62.5% water, the brand-name vodka at 40% is 60% water.  Even bottled generously at 46%, my craft gin and vodka are still 54% water by volume.  With water clearly being the number one ingredient in any bottle of gin, it goes without saying that it must also be the most important.  And it is, but not in the way you might think.

Vodka fresh out of the still is typically 96% ABV, or high enough to shut your liver off like a light switch if you were to drink it.  Gin is made from that same vodka spirit, but redistilled with botanicals and typically comes out of the still at 60-80% ABV, still much too high for drinking neat.  The distiller adds water to reduce the ABV to bottling strength, typically 37.5% for cheap mass-market gin but 41-48% for high-quality craft gin.  Here's a hint: if you see a bottle of gin at 40% or below, you know that profit won out over taste in that brand.

Many distilleries make a big point of telling you exactly where their water is sourced.  It might make the gin sound extra special, but that's purely marketing fluff.  You've no doubt seen this type of claims about distillery water: 

• We use water from a 200-year-old aquifer in the dolomite hills
• Natural spring water from the valleys of Happyshire
• Water filtered naturally through ancient peat beds
• Water made from the tears of hand-flogged Tibetan yaks

The claims about magic water sources can get out of hand at times.  While water is an essential ingredient in any spirit, it's actually more important that the water be absolutely unremarkable in every way.  Here's why.

Every distillery filters its water before using it in their spirits.  This is legally required by every environmental health department in the UK and in fact most of the world.  Even if the source of distillery water is truly exceptional, by the time it gets mixed into the spirit and put in a bottle, it has been through an intense filter to remove any trace of contamination.  This is normally done using a reverse-osmosis filter that effectively removes everything that isn't water.  What is left is very pure, but very bland.  H20 or dihydrogen monoxide, call it what you like, it's just plain water.  Nothing else.

A second reason distilleries filter their water is cosmetic. If water used in gin has residual minerals in it, those will precipitate out of the spirit over time, leaving a fine layer of white dust at the bottom of your bottle of gin.  There's no risk from that, but it can be visually off-putting to say the least.  For these simple reasons, every bit of water in a bottle of spirits needs to be purified before use.  It's just plain water.  It's not special.  If the water were truly special, it couldn't be used for spirits.  On a scale of 0 to 100, the influence of water on the final taste of a gin is just above zero.  The water should have no influence on the spirit other than to reduce the strength to drinkable levels.

There is one exception, which is the water used to prepare the initial brew for distilling.  When extracting starches and sugars from grains like barley or wheat, the chemistry of the water makes a huge difference to the efficiency of the process.  Beer brewers take tremendous care to get exactly the right mix of minerals and acidity for their brewing water.  For beer, the type of brewing water used will effect the final flavour, but once distilled all of these minerals and salts are left behind in the still.  A spirit produced from fermented grain is purely the alcohol created by the yeast and little or no remnant of the original brewing water remains.  Water added later in the process is always purified and filtered.

So where do I get the water for my unique Shropshire spirits?  My water comes from a series of ancient natural sandstone aquifers located between the Rivers Severn and Trent.  That's a fancy way of saying I use tap water processed through a four-stage reverse osmosis filter. It's pure H2O and nothing else, entirely unremarkable but perfect for adding to spirits.

So how important is the quality of water to the quality of a gin or vodka?  It's absolutely essential, but it's important that the water not be special in any way.  

It's just water.