So I recently discovered that Marks & Spencer own-brand tonic water doesn't contain sweeteners. So yesterday I thought I'd revisit my previous taste comparison between tonics, this time including the third contender.
Method
Chilled new bottles of Fever Tree Indian tonic water, Waitrose dry Indian tonic water and M&S Indian tonic water in the fridge.
Poured out small quantities of each tonic into cups and sipped them in turn. Then made 3 G&Ts, each using half a tray of ice, 25ml of Beefeater gin and 50ml of tonic. Sipped in turn.
Results
Fever Tree is noticeably the sweetest drink, although it's still not excessively so. Sipped neat it's well balanced and refreshing. Waitrose is actually labelled 'dry Indian tonic water' on the bottle, and sure enough it is drier, with a slightly stronger taste of quinine. M&S is the blandest of the three. There's a nice scent of citrus to it but when drunk it doesn't taste of very much; it isn't sweet like the Fever Tree but neither does it taste much of quinine. It isn't completely flavourless but it's very mild.
When mixed with gin the sweetness of the Fever Tree is still quite noticeable and honestly a bit unnecessary. The Waitrose tonic, meanwhile, complements the gin well; the quinine is clearly present without being overpowering. As a mixer, the M&S is fairly anonymous. On the plus side, it doesn't get in the way of the gin, but it doesn't do that much to complement it either.
Notes
As before, I used Beefeater gin because it's a good baseline: it's a very traditional gin and not super fancy or unusual, but nonetheless it's also pretty good (especially for the price). It's possible that other gins might benefit more from a sweeter tonic, but that is outside the scope of this ginvestigation.
I also didn't use a garnish in any of the G&Ts. While this would doubtless have improved all three of them, I wanted to focus on the tonic and how it complemented the gin, without too much distraction.
Fever Tree don't use sweetener even in their 'refreshingly light' tonic. While the lower calorie count and sugar content is partly achieved by using fructose in place of sucrose for sweetness, I wonder whether it might also be less sweet than the regular version. This might also be worth trying in future.
Other 'premium' tonics are available, although mostly only online. I remain unconvinced that they are worth the extra expense and effort involved in tracking them down.
Conclusions
As a drink in its own right, Fever Tree is the nicest tonic here; I can easily see myself enjoying this by itself or with a dash of bitters. The Waitrose tonic is also pleasant by itself but the drier, more quinine-heavy flavour isn't quite as easy to enjoy, although fans of bitter flavours might still prefer it.
As a mixer to pair with gin, though, I actually prefer Waitrose. It does have some sweetness but it's subtle enough not to get in the way whereas I find the Fever Tree adds too much. Meanwhile Waitrose has just enough quinine to complement the gin. It's a great combination. And it's also the cheapest tonic here, at 53p/l versus 60p/l for the M&S and ~£3.60/l for the Fever Tree.
The M&S tonic comes a poor third. There's nothing objectionable about it, but it's bland and anonymous. It's still preferable to a lot of nasty artificially-sweetened supermarket own-brands (or Schweppes, which also uses sweeteners and is too sweet anyway), but there's no reason to buy this when the Waitrose tonic is both cheaper and nicer (especially since M&S are really unreliable about keeping it in stock).