In my coffee work my number one frustration is with water. Â I think it is something that has been massively underestimated, both as an industry and very much personally. Â To begin with I knew that hard water was bad, because coffee machines have boilers and you get a build up of limescale. Â The consensus seemed to be that you should throw a simple filter in front of the machine and all would be fine. Â This could not be further from the truth.
First of all – I’ve yet to encounter an ion exchange filter that has effectively prevented scale build up for as long as advertised. Â I’m not accusing manufacturers of being misleading, I just think we have different standards of when water is acceptable. Â When we saw scale building up in customer’s machines we originally presumed it was our mistake, we hadn’t made sound recommendations about how often they should be changed. Â Then we installed flowmeters and we discovered that they simply weren’t effective to the extent required. Â At this point I was a little confused. Â How had everyone else been coping for so long, in London, without having the same headaches as us? Â Part of the reason was that up until about 4-5 years ago there were very few machines with flow restrictors on the hot side of the hydraulic circuit. Â One of the advantages of a heat exchanger is that you can keep your flow restrictor on the cold side, where scale is less likely to build up. Â All of the dual boiler machines that had been coming into the UK had been unrestricted. Â As people began to demand flow restriction as standard we began to see these issues crop up. Â The other side of the coin was that a number of companies were actually pro-scale because it was a good source of aftersales revenue through servicing and descaling.
Even when you are on top of your ion exchange filter – they’re still not ideal if you are looking for the best cup quality. Â While they’ll remove bad tastes from the water, they don’t massively reduce the overall TDS (total dissolved solids) in the water. Â Typically we wouldn’t see much below 250ppm, and though this water would be unlikely to produce scale inside a machine it wasn’t the greatest solvent in the world for getting the best out of your coffee.
This is as much a public catalogue of errors and learning, because at the time we genuinely thought this was the best solution. Â We didn’t realise how bad things were, and what kind of measures were actually necessary to take. Â John Gordon took on the burden of learning a lot more about this, and has done a huge amount to share what he has learned. Â I’m incredibly grateful to him for dragging me by the heels into this stuff.
The current solution
Here is pretty much where we are now (though bear in mind this may change as we continue to learn):
If you are in a hard water area and are interested in best possible cup quality, and in keeping your machine in goodÂ conditionÂ then the only viable choice is reverse osmosis (RO). Â This is painful news because the initial cost of an RO unit is several times that of a simple filter. Â They are also bigger than a filter. Â They are also less water efficient. Â Not all of this is good news – but when you are dealing with water with total dissolved solids at upwards of 450 ppm and calcium hardness at 300 ppm then you have to accept that local geology has stacked the deck against you and it will be an uphill battle.
More than 9 out of 10 machine service issues we deal with are due to a build up of scale. Â I don’t think we are alone in this statistic, as a company working in a hard water area. Â There are a number of companies who provide solutions, and this isn’t the place to recommend any particular one. Â Support and service are a big part of any equipment purchase – and these can vary by country and location.
I don’t like that RO is the way forward, but I like it more than how coffee tastes when the water is bad even less. Â I am sure that right now there is no better solution and that a unit is worthwhile investment. Â If you are thinking of opening a shop in London, or any other hard water area then I beg you to build one into your budget. Â If you have an existing shop in an area like this and you haven’t looked into it then I’d suggest doing so strongly – you may already have experienced (several times) what happens when limescale attacks!
In my own experiences (which are relatively limited) I’ve found myself enjoying coffee close to the SCAA’s published specificationsÂ (pdf)Â as used at WBC and the like. Â I know other people have had good results at very low TDS levels, but I think the chemistry of the water makes a big difference here. Â I’ve struggled with water much below 80ppm (with our coffee) but I’ve had great coffee in places like Oslo that have water around 40ppm (correct me if I am wrong). Â This means that there is no hard and fast rule with low TDS water – it is, like everything in life, more nuanced than that.
Where we need to go next with water
We need better understand of how the exact makeup and composition of the water impacts coffee brewing. Â So far I have only mentioned Total quantities, and levels of carbonate hardness. Â There is typically a lot more in the water, and I haven’t even brought up stuff like pH and its impact yet. Â This is because we’re still a little unsure. Â Using things like the Langelier IndexÂ we get little insights into how water may behave inside our equipment, but not with our coffee.
Where everything really breaks down for me is when people brew coffee at home. Â Right now, for domestic consumers of coffee in London, I don’t know what to propose. Â Tap water makes all coffee taste generic, boring and unpleasant. Â Right now we’re mid Kenya season, but a great coffee from Nyeri brewed with London water just tastes brown and sad. Â None of the stunning fruit goodness, that justifies the pricetag, is available to the person who bought the bag – simply because they live in the wrong part of the UK. Â Filtered tap water (through a Brita filter or similar) certainly tastes better, but it is mostly just a taste and odour filter and it barely reduces hardness – the TDS remains too high to make truly excellent coffee.
Am I then left to suggest that they buy bottled water? Â Should I recommend certain brands, or try to explain how to read the mineral content that they must publish on the side of every bottle? Â Do I try and get people to install domestic RO units (which isn’t actually super expensive, but many people rent and may be unwilling to attack their own plumbing without expensive professional assistance)? Â Should cafes with high capacity RO units be selling that water very cheaply to go along with the bags of coffee they retail? Â (I like this idea – if the bottles can be done in a sensible/sustainable/not really heavy to carry home way).
This is a big problem. Â This is not a universal problem, not in the UK, not in Europe, or in the US or the rest of the world – but it effects a massive number of people who drink and enjoy coffee. Â We’re not discussing this enough as an industry (despite the best efforts of John and others) and we don’t have a coherent solution. Â We can’t stick our heads in the sand on this any more.
There is a discussion hosted on branch here. Â I’d love to see people tackle this problem, and offer up some ideas on how we move forward. Â (I’m going to try and keep this one on topic, so access may be limited to those who offer some insight in their request)