We all know water is very important in brewing coffee but its also crucially important in tasting coffee. When you think about a filter coffee, most of the time we’re looking to deliver something thats nearly 99% water whilst espresso is almost 90%. The water we brew with is not just a vehicle for brewing but actually the main constituent of the product we make and sell by quite a substantial distance.
To put that into context, there is more water in green coffee by percent than there is coffee in a drip filter. There’s also pretty much the same amount of water in green coffee as there is coffee in an espresso*. Applying one logic to the other we could get away with calling green coffee “water”. We won’t though.
Water is undoubtedly important in terms of extraction but the impact it has on flavour is a completely different issue that is often lumped into the same category. They are separate issues that should be addressed independently and one should always bear in mind that you can have many different waters with the same TDS that impart very different flavours on the water.
The water itself can have many different chemicals, minerals and additives and can also be affected by how its heated and dispensed. Aeration of water through a dispersion screen will have a big effect on the flavour in the cup, especially where the water has remained stagnant after boiling.
This post is about 2 years too late in a way as its based on some experiments I did in 2010 leading up to the 2010 WBC. I ended up designing a signature drink that comprised of the same espresso diluted with 2 different types of water in order to highlight different flavours in the coffee.
The two waters I used were actually distilled water I bought in a Pharmacy (TDS 0PPM) and a bottled water (TDS 470PPM) that I bought in Tesco. The distilled water highlighted the floral, fruity and acidic flavours whilst the bottled water made it earthy, woody and viscous. It was a real eye-opener to me and when I came up with the idea I didn’t fully expect it to work as well as it did.
This was undoubtedly my favourite signature drink I’ve ever made, though undoubtedly an unnecessarily risky one. In my finals round I scored a 5, 4.5, 4 and 3.5 as well as a 2 from the head judge. In truth it probably would have been better to use it as a blog post instead of a sig drink. Mia culpa.
Until this point I always believed before this that water should be neutral when you’re brewing but I now believe thats actually impossible. Water will always have a flavour and that will always be reflected in your final cup. You should treat water as an ingredient and not just a flavour conduit.
The idea of this experiment is to taste the effect that water has on coffee and not the effect it has on the extraction. Therefore what you need to do is to brew a coffee and with a high TDS and then dilute it with different waters to see the flavour it imparts. The beauty of this particular test is that its one you can try tomorrow while you work without much prep at all.
The best way to do this is to heat the water in non-metalic vessels (I use a syphon bulb and burner) so as not to impart flavour on the coffee and then use the various waters to dilute the high-TDS coffee. I’m sure you could also use a microwave but I haven’t tried this yet. I know someone who has though.
The easiest way to do this is by brewing espresso (one for every sample cup) and mixing all the espressos in a large jug so that all the sample cups have the same coffee. The chances of brewing identical espressos 4 times or more in a row are unfortunately unlikely. I’d also recommend you filter the espressos for more clarity.
You can also opt to brew a “regular extraction” but high TDS filter coffee and use that as the sample. I wouldn’t attempt this method without an Extract Mojo or TDS meter so that you can check the TDS as you go. It is also vital to use an accurate digital scale when diluting the coffees so that you add the same amounts of water to each sample.
So, once you’ve got your coffee sample the basic idea is to take the same coffee sample into a a number of different cups (e.g. 6 cups for 6 samples) and dilute the sample with different waters to see how it changes the taste. If you can use scales, temp probes, mojos, TDS meters and other gizmos then great. If you can’t then don’t worry about it, just have a go and you’ll definitley learn something.
Here’s some suggested waters you should add to coffees to be cupped;
Various bottled waters (The TDS is usually displayed on the side panel or can be calculated easily)
Water heated to 85c
Water boiled and cooled to 85c
Water from your espresso machine hot water fosset
Water from your boiler
Filtered water from a different city heated to same temperature
Water poured carefully and slowly
Water whisked, splashed and stirred (aerated)
Post filter water
I’m sure there’s many other types of waters that you can try and each will yield different results. If you want to keep it simple and get dramatic differences I’d go with distilled vs high TDS bottled water. Enjoy and let me know how you get on
*estimated at 10.9873987598798398% by one particular coffee maverick