When I was at Costco they were fairly low on bottled water choices suitable for espresso machine use. There was the Kirkland brand of "Alkaline Water", and GLACÉAU SMARTWATER, neither of which actually posted a water analysis on the label. So I just grabbed a case of the GLACÉAU Smartwater to use in my Decent.
Anyone have opinions on this product?

They unfortunately don't publish full water quality reports - they have a "sample" report on their FAQ from 2018, but it's purely pass/fail with limits set at levels that would destroy an espresso machine (500ppm TDS - I know this isn't directly harmful but it's highly unlikely that Hardness is low enough with this, 250ppm Chlorides): https://www.drinksmartwater.com/content ... 0FINAL.pdf

Having said that, it's distilled and re-mineralized, so it just depends on how strongly they remineralize, and what they remineralize with. This next link (which I have no knowledge of, other than Google sent me there - they may or may not be competent) says basically that TDS is low for all the variants (<50ppm) so it doesn't seem to be super high risk: https://testaqua.com/usa-water/smartwater-water-test/

You were wise to avoid water marketed as 'alkaline' water. So-called alkaline bottled waters have a too high pH, and likely too much of an unknown mix of minerals for coffee machine use.

That Smartwater has minerals added for taste, which they do say on their site includes potassium bicarbonate, calcium chloride, magnesium chloride, and sodium selenate. The sodium selenate would be in trace amounts, so most of the TDS readings would be due to the chlorides and bicarbonate. If they were to add equal masses of those three salts at 10 mg/L it would read about 30 ppm on an inexpensive TDS meter, which is about what people report online for this water. That's enough for the machine's water sensors to work. But the alkalinity would be too low (around 5 mg/L CasCO3 equivalent) for corrosion protection. And that chloride is certainly not ideal (any chloride may be corrosive.) It's not above alarm levels -- this conjectured mix would have about 10 mg/L chloride ion.

But it's certainly not ideal for espresso machine use. If you do use it add a teensy pinch of sodium bicarbonate (baking soda, about 0.3 gram per gallon of water) to bump the alkalinity.

Thanks you Pat, It's too bad if I can't use it because it's super convenient. The 1L bottles almost fills my Decent water tray.

Stated above," But the alkalinity would be too low (around 5 mg/L CasCO3 equivalent) for corrosion protection", however you said to add a pinch of soda but wouldn't that just drive the alkalinity further?

Willinak wrote:Stated above," But the alkalinity would be too low (around 5 mg/L CasCO3 equivalent) for corrosion protection", however you said to add a pinch of soda but wouldn't that just drive the alkalinity further?

Yes, and that's what you want. Typical advice is to make sure your alkalinity is at least 40 mg/L. Even if you were to add a little too much bicarbonate it would still be machine healthy and the espresso should taste fine.

Pat, a followup question: if I were to use the BH formula which uses sodium bicarbonate and epsom salt in distilled H2O, can I use the same weight of potassium bicarbonate or what would the equivalency be?

Willinak wrote:Pat, a followup question: if I were to use the BH formula which uses sodium bicarbonate and epsom salt in distilled H2O, can I use the same weight of potassium bicarbonate or what would the equivalency be?

If substituting potassium bicarbonate for sodium bicarbonate in a recipe you just use a little more by weight. Multiply the amount of sodium bicarb by 1.2 to get the amount of potassium bicarbonate that will give you the same chemical equivalency.


If using the Matt Perger two bottle recipes where he says:

The Buffer Solution
Dissolve 1.68g of sodium bicarbonate in 1L of deionised water. This creates a solution with a KH (as CaCO3) as close as we can get to 1000ppm.

you would use 2.0 grams of potassium bicarbonate to get that same 'KH' (alkalinity as CaCO3) of 1000 ppm.

A wealth of information, thanks Pat!