Cambridge Water for Great Coffee

Cambridge is an outlier in terms of water chemistry in the Boston area. Most cities and towns around Boston source potable water from the Massachusetts Water Reservoir Authority system; Cambridge goes it alone and uses its own systems (except on an emergency basis – shortages – when it pays for MWRA supplementation.) There are historical, practical and cost reasons behind this approach, and Cambridge provides safe water at lower cost than if it were to source from the MWRA. However, Cambridge water goes through intensive treatment and as a result, has three characteristics which create challenges for coffee shops.

Cambridge tap water is high in total dissolved solids (TDS). Pre-filtration, the TDS at our shop is over 450ppm and the official Cambridge data puts it at 472ppm (as of 2018). To put this in context, MWRA water ranges between 50-150ppm and the Massachusetts Department of Environmental Protection puts the threshold for public drinking water at 500ppm. Water with a high concentration of existing dissolved solids is generally less effective as a coffee flavor solvent – which means that untreated, coffee brewed in Cambridge will tend to be under-extracted. What solids are dissolved also influences the flavor of the water (and thus the coffee) as well as the balance of what is pulled out of the ground coffee. Assuming a proper balance of minerals and bicarbonate, we believe that between 75-150ppm water is optimal for extraction and flavor.

Cambridge tap water is high in total dissolved solids (TDS). Pre-filtration, the TDS at our shop is over 450ppm and the official Cambridge data puts it at 472ppm (as of 2018). To put this in context, MWRA water ranges between 50-150ppm and the Massachusetts Department of Environmental Protection puts the threshold for public drinking water at 500ppm. Water with a high concentration of existing dissolved solids is generally less effective as a coffee flavor solvent – which means that untreated, coffee brewed in Cambridge will tend to be under-extracted. What solids are dissolved also influences the flavor of the water (and thus the coffee) as well as the balance of what is pulled out of the ground coffee. Assuming a proper balance of minerals and bicarbonate, we believe that between 75-150ppm water is optimal for extraction and flavor.

As a result of water facility treatment, Cambridge water also has a surprisingly high PH, 9.1 according to Cambridge Water Department figures. One of the final steps in the water treatment process in Cambridge is to increase the PH for corrosion control to reduce the propensity of water to leach lead and copper from the service lines and home plumbing systems. Although the water is treated with sodium hydroxide, not sodium bicarbonate, it has a distinctive salty, chalky, baking soda like taste to it.

Finally, Cambridge water has a high chloride count – officially 236ppm (vs 50ppm or so in most MWRA locations, and a maximum DEP guideline level of 250ppm.) Under heat and pressure, the chlorides can acidify (think hydrochloric acid and sulfuric acid) to the extent that water that started with a base PH, ends up being surprisingly acidic. Indeed, Cambridge is known in the espresso machine manufacturing industry for having a disproportionate number of boiler failures related to acidic water and some manufacturers now require Cambridge cafes to install sophisticated filtration systems as a warranty condition.

At Broadsheet, we have made significant investments in water filtration . We have a large primary filtration system of the sort used in many breweries. All water that is not fed to the toilets goes through this carbon and sediment filter combo. This helps, but can’t come close to solving the TDS, PH and chloride problem. Water intended for consumption is thus fed into a secondary system: an efficient reverse osmosis unit which produces water that is pretty close to distilled. Extremely low TDS water, however, doesn’t make for tasty coffee (it can be harsh, over-extracted, and thin). The tank of our RO system is equipped with a sensitive TDS meter, connected via a control loop to a peristaltic pump that drips a mineral solution into the tank to allow us to achieve and precisely maintain our target TDS count and mineral balance. We keep this steady throughout the year (TDS levels in the water supply fluctuate seasonally) which allows us to minimize the variables with which we must contend in brewing and to optimally and consistently extract our coffee. The primary filtration system and RO unit aren’t cheap, but we feel they more than pay for themselves by protecting our equipment, and of course by allowing us to consistently brew the best coffee and tea we can – which is after all our raison d’etre.

For further reading on the topic of water and coffee, Chris Hendon and Maxwell Colonna-Dashwood’s Water for Coffee is the go-to book on the subject, and Scott Rao, Matt Perger and Jim Schulman (and others I’m sure I’m omitting) have all also experimented with and written extensively on the subject.

Additional information on water in Cambridge and the MWRA is available via the following links.

Cambridge’s water treatment methodology:

Cambridge’s most recent (2017) water quality report:

MWRA’s 7/2018 water quality report:

MA Department of Environmental Protection Drinking Water Guidelines:

The Americano

Years and years ago, I worked on the vast and bustling trading floor of a big bank overseas, part of a small trading team composed largely of nerdy Americans.  Every Friday, and to the great hilarity of those around us, a couple of enormous British bond salesmen would deliver coffee to us – short Americanos, of course.

Ah the wit!  Anyway these memories of a gilded age aside, prior to opening a coffee shop, I never thought much of the Americano.  To be frank, I used to consider it an inferior drink: usually crappy espresso diluted with boiling water.  As a cafe owner though, I definitely appreciate the rationale behind the beverage and now largely take issue only with its preparation.

There are plenty of good reasons for the Americano even for cafes with great batch coffee (like us!).  For many customers, this is just their default order.  Perhaps they’ve been traumatized by bad batch coffee, or simply like espresso but find it too strong.  Espresso, after all, is what to many makes a cafe special.  Or perhaps they like the “richer” mouthfeel of an Americano, given that more coffee oils pass through the metal espresso portafilter basket than the paper filter typically used in batch brewing.

There is a second category of “why” that is a bit more specific to our shop.  We don’t sell tons of decaf, and of the decaf orders, a number are “half-caf” (hard to accommodate with a standard set-up).  Rather than dedicate an under-utilized grinder to decaf (fated to be infrequently dialed in and either purged at the end of each day, wasting a ton of coffee relative to the amount used in beverages, or left with a full hopper of oxidizing beans) we always have small amounts of fresh decaf on hand which we single dose in our EK43 grinder (in a ratio of caffeinated to decaffeinated beans to suit the order).  We don’t do pour-overs, so the Americano is the most efficient way for us to serve decaf cups of coffee.  The second shop-specific reason is that we roast coffee on a spectrum from light to medium, but never dark.  The single origin we use as our “House” espresso is roasted a bit darker than most of the other coffees on our roster, and tends to have a more familiar “comfort cup” profile.   So when a customer asks for a “dark roast”, we generally offer them an Americano, which almost always makes them happy.

In any event, the Americano is a surprisingly popular beverage and something cafes really should prepare well, but I suspect too few do.  There are many pitfalls (at least to make the type of Americano that I enjoy).  First, many shops, even amongst the most progressive out there, use a more traditional Italian-influenced house espresso (a darker roast typically involving South American and naturally processed beans).  I don’t feel that these espressos translate well to Americanos as they don’t have a lot of flavor clarity; diluted with water, they can thus tasty murky and ashy.  Second, it is very hard to properly extract espresso.  To hit a 20-22% extraction (a pretty optimal range for the flavor balance you’ll really taste in the slowed-down experience of a longer drink like an Americano), you really need a first rate and well maintained grinder and a higher ratio of beverage mass to ground bean dose than typical.  Third, I feel that most Americanos are way too diluted, and in order to get the beverage strength right (ideally somewhere between 1.25-1.5% coffee matter), the Americano probably can’t be a full 12oz unless the shop doses their espresso with 20g+ of coffee (and extracts >20%).  And finally, the water used in the cup shouldn’t be >200F (even though many customers like their Americanos hot.)  With water that hot, the beverage will be a lot hotter than most batch coffee, and customers risk burns and can’t taste anything but “hot”.  Although I’d really like to use 175F water, to balance taste vs demands for “hot”, I prefer using 190F water.  And the water should never be drawn from the espresso machine hot water dispenser (both as this is way too hot and to preserve the longevity of the machine).

Anyway, these gripes reflect my personal preferences – but also a consistency with general principles of brewing and crafting quality beverages.

The Ikawa Sample Roaster & survivor bias

One of the many routine tasks in a coffee roasting business is sample roasting.  We’re constantly receiving small quantities of different coffees from green coffee importers, and we need to figure out whether it makes sense to buy any of them.  Sample roasting is time consuming, and tbh, not a lot of fun.  The goal is to roast the different coffees to a similar roast/development level so that they can be evaluated apples-to-apples (without differences imparted by variations in roast).  So the goal isn’t necessarily to bring about the best in each coffee, but just to stick to a process. It can also be stressful: typically you roast a lot of samples at once, and some green coffee importers only send enough of a sample to allow for one, possibly two roasts….you don’t want to make a mistake as green coffee buying is a speed game, coveted coffees go extremely quickly.

Enter the Ikawa. It looks like a glorified electric air popper, and it kind of is. However, it is a lot more robust, has a fast thermocouple (which reads the air temp right above the rotating fluid-bed-y coffee mass as a proxy for bean temp) and a PID linked to an iOS app which allows you to program profiles for the time-temp path you’d like the temperature readings to travel. It also has a very clever built in chaff separation mechanism, and a roasted bean cooling function. Finally, it has created a great community around the sharing of roast profiles, and it is easy to send profiles to others so that you can roughly sample roast in the same way.

I could write another blog post on profile creation and the different approaches for different origins/processing methods, and whether I think a PID which forces the roast along a prescribed path is an optimal way to go about roasting coffee.  But suffice to say that basically, the Ikawa dramatically simplifies workflow and churns out pretty decent sample roasts. Load a profile onto the machine via a Bluetooth enabled iOS device, hit a button, wait until the Ikawa warms to the charge temp, load the green coffee, and wait for a chime to go off 7-8 minutes later to let you know the roast is done. You can even do other things while the coffee is roasting which is kind of incredible for a roaster.

So it is no wonder that the Ikawa roaster is taking the roasting and green coffee end of the supply chain by storm. It makes sample roasting so much easier and efficient. In tandem with this, I see more green coffee importers offering roasted samples of coffees in lieu of green coffee samples. Makes sense: it’s less work for the roaster, the Importer is ensured that the roaster is giving the coffee a fair shake (ie hasn’t done horrible things to the coffee while sample roasting, and is actually going to cup the samples!) and reduces waste (just one 50g sample bag, not a larger amount of green, some of which will inevitably be wasted).

When you receive roasted coffee samples, however, you are deprived the opportunity to examine and grade the green. You can’t count defect number and type, nor can you read the moisture and the like. So you need to be sure that the roasted coffee you receive accurately reflects what is inside the 150lb bags of green coffee you’ll be buying. Every green importer I’ve dealt with has been honest to a fault and would never groom green samples and remove defects. However, when it comes to roasted samples, I think there is an inadvertent source of bias that perhaps many importers and roasters don’t consider when evaluating the coffee.

The Ikawa sample roaster is pretty close to being a purely convective roaster, the coffee makes very little if any contact with metal surfaces, and thus heat transfer occurs entirely via hot air.  The green coffee is held aloft by the force of the air, kind of in the same way that a hovercraft floats over the water or ground. So airflow is by necessity high, and I believe proportionally higher in the Ikawa than in more traditional open faced sample roasters (or any traditional drum roaster for that matter). Ikawa cleverly uses this high airflow to loft away the chaff (which is far less dense than the coffee) into a catch “cup”. But quakers and many other types of defective beans are also less dense than the more perfect ones, and these are jettisoned with an alarmingly high efficiency into the same catch cup too. So, if you are in a hurry and dump the contents of the catch cup without pulling the quakers (and at times it can be hard to see the light colored beans in the fluffy chaff), you are basically grooming the coffee of defects and creating a sample that is better than – and not accurately representative of – the actual coffee lot under consideration. It is certainly the case that all roasters will suck up some quakers into their chaff-clearing cyclones; but from what I’ve seen, the Ikawa removes more defects as a percentage of the total defect pool than other roasters.

This might not make too much of a difference for extremely clean and well processed coffees with very few defects/quakers (typically these are very high scoring and pricey coffees). But in most samples of even decent specialty coffee, you’ll find a surprising number of quakers and other mild defects. In mid-range specialty coffee, I often find around half the quakers and other obvious defects in the catch cup; in a 50g Ikawa roast, this means that I might find as many as 3-5 defective beans in the cup (on the order of 1% of the total 50g!)  To me, this is pretty significant and to the point where I believe it’s impacting the cupping scores. And also quite telling is that most of the beans that end up in the catch cup are quakers and not viable coffee (good beans also make it into the catch cup, but in lower numbers, and thus at a much lower percentage of the total amount of good beans in the sample).

This is not to disparage the Ikawa, it is an awesome machine. I just want to point out that a by-product of its chaff clearing system – that is ironically perhaps too good – is that the user could be left with a cleaned up pool of coffee and should factor that into the evaluation process.

Drink it like a customer!


We’ve recently revamped a number of beverages on our menu. The re-think was prompted by the realization that we need to systematically try each beverage on our menu the way our customers typically drink it. This seems so obvious in hindsight, and I’m sure that plenty of others have said this (and done this!)

One of the dangers in this business (and perhaps life in general) is assuming other people share your priorities and preferences. I’m a coffee roaster and thus very focused on our filter/batch (hot and iced coffee) and espresso as these drinks are the most transparent to the quality of our coffee and roasts. But of course I also follow the sales numbers and thus pay a lot of attention to the core milk drinks: Lattes, Caps, Cortados etc. If we aren’t super careful with the biggest sellers, we’ll alienate our core customers. And similarly, lots of customers take their coffee with milk and sugar, so we’re careful that our batch hot and iced coffees go well with these too.

But with the attention on the core drinks (and the ones that staff tend to order,) several drinks on the menu didn’t get the attention they deserved. Iced black tea and iced chai for instance. We use a phenomenal Golden Needle oolong from Song Tea as our house black tea; it has remarkably low astringency for a black tea. We made the mistake of assuming that because it is great hot, it’ll be great cold, and confirmed this only by tasting it straight. And of course we already have this tea in-house, so using the same was the path of least resistance. However, loaded with melting ice cubes and milk, the tea was unmemorable. Similarly, our chai spices were lovely and delicate and worked reasonably well as a hot chai. But chilled, when our ability to taste spice and sweetness is lower (try room temperature melted ice cream,) the chai was outright weak and watery. And so on. So we’ve completely redone some of our recipes and approaches, covered up our bare spots so to speak. If it’s on the menu, it should be great – the way customers want to enjoy it.


Honduran Coffee and Varieties


Honduran coffees get a bit of a bad rap.  Outside of coffee circles, they aren’t terribly well known (or perceived), particularly relative to coffees from Guatemala, with which Honduras shares a coffee-producing border.  This is unfortunate, as Honduran coffees can be absolutely stunning.  This year’s Cup of Excellence (COE) winner in Honduras scored a 91.81 and fetched $124.50/lb; the winner of Guatemala’s 2017 COE scored 90.36 and sold for $58/lb.  I mention this with no slight intended toward Guatemala – which produces some amazing coffees – but only as a mode of illustrating that Honduran coffees can compete.

Back in February, I was lucky enough to participate in a week-long trip to Honduras sponsored by Volcafe/Genuine Origin. I learned a ton on the trip, but what is relevant for this post is that I was exposed to not only some great, perception-changing coffees, but also a wide range of taste profiles.  I had no idea that some Honduran coffees possess intense malic acidity, while others are of the comfort-cup or earthy-herbal ilk.  Part of this is clearly a function of terroir and processing differences intra-country.  But I suspect a large reason for the massive differences in taste that I experienced relate to coffee variety (think Pink Lady vs. Macintosh vs. Granny Smith).

We are currently offering two extremely different Honduran coffees.  Los Yoyos is a legendary coffee that won the 2015 Honduran COE.  It is 100% Parainema, a hybrid developed between Costa Rica and Honduras as a cross between Villa Sarchi (a highly productive Costa Rican Bourbon variety, similar to Caturra) and a Timor Hybrid (ie, with some Robusta lineage).  The name gives it away, (para = against, nema = nematodes) – it is resistant to both leaf rust, and predators.  Despite its inauspicious origins and name, it is delicious, with a truly wild taste profile (think passion fruit and lemon curd).  Los Yoyos of course isn’t a run-of-the mill Parainema, it has been exceptionally processed and sorted (it is perhaps the most beautifully processed coffee I’ve ever roasted).   The other Honduran, also from the same region of Santa Barbara, is El Tanque, produced by the famous Moreno family.  This is a much more familiar cup, delicious with caramel, dark chocolate, tangerine and peach.  It is Catuai, a Brazilian Caturra hybrid.  Same region, similar terroir and processing, different variety, dramatically different taste profile.