How long do you let water sit in the boiler between uses?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
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thevitruvianman
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#1: Post by thevitruvianman »

I just acquired my millennium, and I know it's a really simple question, but should I worry about leaving water in the boiler if the machine won't see use for a certain amount of time (days, weeks, months, etc)? Is there a general "dump it" rule of which I'm unaware to avoid excessive scaling or other unforeseen issues from the stagnancy?

Thanks

Jake
"I'm tired of being caught in the tangle of their lives."

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rpavlis
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#2: Post by rpavlis »

I would say that it depends on two things: The amount of contaminants in the water you use and how much steaming you use. ( If your water have certain contaminants, microorganisms could also begin to grow in it if you fail to use the machine frequently enough. This can produce an extremely hideous taste.)

Steaming removes essentially water only, leaving behind contaminants, so the more you steam, the more contaminants are in the boiler. Although you lose contaminants when you make the espresso, contaminants still are increased.

Many municipal water systems have wildly fluctuating compositions, especially ones that get water both from wells and streams. Bottled water is also far from analytical chemistry grade solution too. If you have your own well, the fluctuations will be fairly small. The only way to have NO fluctuation is to use either pure distilled water or deionised water, or to use these and deliberately add the components that you want in it. Either way the variables are all under YOUR control. Although some think it egregious, I prefer straight distilled water with medium-dark and dark roast, and 1.0 millimolar KHCO₃ (potassium bicarbonate) for light to medium light roasts. This also turns out to be near the conditions that provide maximum protection from corrosion. (I have discussed making this before, get potassium bicarbonate from some health food stores or other places, dissolve ten grams of it in 100 mL of water, add 1 mL of it per litre of distilled water. It has about the same bicarbonate concentration as moderate hard water, but does not have the Ca or Mg to create scale. Ca and Mg are in the coffee beans in great quantity already.)

You can also use ordinary baking soda, it is NaHCO₃, you can make a 4.2% solution of it, and add 2 mL per litre of distilled water.

With either pure distilled or 1.0 millimolar bicarbonate solutions you can go months without dumping the boilers, and you will never have scale. It also completely removes fluctuations of contaminants as a variable in coffee flavour. Of course you could add other things to it, but I would avoid any chlorides or sulphates.

EspressoForge
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#3: Post by EspressoForge »

As Robert mentioned, it would really depend on the water that you use. But assuming you use water optimum for coffee with some TDS, but not distilled water...I would say generally keeping the water around and topping up for a week would be just fine. On the weekend you could recycle the water just as a routine. Again depending on actual TDS and how much you steam, you could probably go a lot longer, or if you have very hard water, you might think about dumping and refilling every session, or every other session.

If you're going on a vacation, or don't plan to use the machine for a while, I would always drain it and tip it over to let it dry out completely inside.

OldNuc
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#4: Post by OldNuc »

The best tasting coffee I have ever had was made with deep bed demineralizer pure water produced with charcoal inlet filter, cation deep bed in H form, degasifier, anion deep bed in OH form, and a deep bed mixed bed polisher. This is absolutely pure water in a highly ionized state.

Robert is spot on with the suggestion to use distilled water with only a trace of potassium or sodium bicarbonate if you have to see an increase in conductivity above zero.