Attack of the Killer Scale
Look, we're not joking. Yes, there are a lot of things we poke fun at and crack wise about, but scale build-up in your boiler is absolutely not one of them. And it will never be -- oh no, we are deadly serious about this.
Okay, not really, but scale build-up is often underestimated by folks. They think that by using filtered or bottled water, they won't need to descale their espresso machine, and this just isn't the truth. While these waters may have other impurities removed from them, they often have the same mineral content (and, in the case of bottled water, it may even be significantly higher, depending on the source) as your tap water. Using distilled water, water put through a reverse osmosis or a commercial-grade water design system like Cirqua are the primary methods for keeping lime and calcium from building up in your espresso machine's boiler and related water works, but it's important to note that mineral content in water does play an important role: It contributes to the flavor.
So if you don't like the way the water from these treatment sources taste, how do you think it's going to make your coffee taste? We recommend using water you like to drink to make espresso, which will often involve a regular descale to keep everything working well. Scale build-up will symptomatically show up as failure or very slow to heat up, not enough steaming pressure and/or leaking out of the steam wand and the brew head. Here in the Seattle area, we have pretty soft water, but other areas of the country have very hard water -- and if you're pulling straight from a well instead of the municipal water supply, you likely have a high mineral content.
A few months ago, we received a Rancilio Silvia V2 that was a few years old on a trade-in. The owner lived in Southern California and had never descaled the machine, so the guys put it through a commercial level descale just to start it off -- high intensity citric acid was pulled into the boiler and allowed to sit overnight. When they came in the next day and rinsed it through, the machine was still exhibiting signs of scale build up, so they decided to crack it open to see if it was something more than scale. What they found is in the pictures accompanying this post -- yes, this is scale build-up that was not able to be dissolved by the citric acid over a 24 hour period. The guys cleaned it out thoroughly and now it's working just fine -- and, obviously, this is representative of scale build up using the municipal supply in Southern California and will differ by region -- but if the original owner had continued to use it without descaling, eventually everything would have burned out. It was caught just in time, however, so now it has a happy home somewhere else.
Not sure how to descale? Watch Gail descale a Rancilio Silvia and give tips on how to do this on other types of espresso machines.