JHCCoffee Safe for Lelit Elizabeth use, without the Lelit filter?
It depends on what you mean by ‘safe’. It will almost certainly scale, considering it has a fair amount of Mg and Ca, and relatively high alkalinity. The problem is that what isn’t known is the origin of the alkalinity, and the lab haven’t provided a concentration of (hydro)carbonate ion. If it comes all from organic acids (e.g. citrate), it may be ‘safer’ than if it comes from carbonates, however this is very unlikely to be the case - see the ‘nerdy’ section below. It also has a fairly high amount of sulphate, likely coming from the addition of magnesium sulphate (Epsom salt).
Can you use it in a machine without catastrophic effects? Yes. You will need to flush and refresh water in the boilers quite frequently, and you may need to descale every so often. How ‘frequently’ and ‘often’ depends on how you use the machine.
Would using the Lelit filter help? Yes for the scale; but you then may as well feed RO water into the machine, possibly adding some bicarbonate (sodium and/or potassium) to increase alkalinity, and skip the cost of the TWW sachets and of the Lelit filter, since you’d be taking out with the latter most of what you are adding with the former.
JHCCoffee Likely to produce good tasting espresso (if all other factors are equally well addressed)?
Very likely, though there is no accounting for personal taste. It’s very close to SCAA recommendations in terms of many parameters, which is probably what TWW aimed for.
JHCCoffee Better or worse than other water recipes you have used?
It seems to be a fairly average recipe containing Epsom salt (MgSO4), cooking salt (NaCl), and ‘something’ with calcium and potassium that has also added alkalinity - since the lab hasn’t told us what it is… we are left guessing a bit. It’s significantly more alkaline and rich in Ca and Mg than anything I would want to use for any length of time (as it would impose a frequent maintenance schedule that I can’t be bothered to do!)
The nerdy chemistry bit - with some of my guesses as to “what’s in the TWW bag”.
I’ve done some stoichiometric calculations, and, making some assumptions, everything seems to work out very well:
The RO water was substantially pure. I know they say it has 28 ppm of dissolved solids, but a) we don’t know what they are, and b) I suspect that’s the maximum amount of TDS that they would tolerate before changing the membranes.
The recipe consists of a mix of the following:
MgSO4 as the source of magnesium
Ca citrate as the source of calcium
NaCl as the source of chlorides
and other undetermined salts containing potassium.
Given the above assumptions, we note that stoichiometrically:
a. The magnesium and sulphate amounts are in good agreement with MgSO4 being the source of all the Mg and sulphate in the water.
b. Assuming all chloride is being introduced as NaCl, this leaves an ‘excess’ of 8.2 mg/l of sodium.
c. Assuming the excess sodium and all the potassium were introduced in the form of their respective bicarbonates (hydrocarbonates) results in a calculated addition of 30.0 mg/l of NaHCO3 and 43.8 mg/l of KHCO3
d. Assuming all the calcium is introduced as Ca citrate, this corresponds to 73.1 mg/l of citrate.
The resulting solution has a calculated KH of 72.3 and GH of 149.5, which matches rather well the lab measured amounts. This seems to be obtained with the following recipe (rounded to the nearest mg, and based on measured rather than calculated values where measurements are available):
- MgSO4 · 7H2O 270-280 mg/l
- Ca citrate 89 mg/l
- NaCl 9.4 mg/l
- NaHCO3 30 mg/l
- KHCO3 44 mg/l
If this is correct, ~⅔ of the alkalinity comes from (bi)carbonates, which makes it certain to form scale in both service and brew boilers.