akirapuff wrote:So there is a possibility that it will corrode my machine?
Possibility yes, because corrosion experts say that any chloride may be harmful and the current advice about alkalinity is to keep it up near 40 mg/L - but that water is not seriously bad and any corrosion may take a long while. That water is similar to the Gerber Pure remineralized baby water that is relatively popular for use in espresso machines and we haven't heard negative reports about that. (Gerber Pure has slightly better alkalinity and slightly worse chloride than this remineralized Pure Life water.)
akirapuff wrote:Also if i felt inclined to keep using this water, what kind of treatment(epsom,bicarb?) do you recommend to make it suitable for espresso? Thanks much in advance!
A simple bicarbonate spike would help.
You'll see many references in this forum to "rpavlis water" which refers to chemistry professor Robert Pavlis' water recipe. (HB member rpavlis, RIP) -- which is purified or distilled water spiked with 50-100 mg/l of potassium bicarbonate.
From 1977 La Pavoni Europiccola with green deposits/scale
rpavlis, in linked post above wrote: .... I personally use, as I have stated many times, about 0.5 to 1.0 mMolar potassium bicarbonate. You can simply add from 250 to 500 milligrams of potassium bicarbonate to a 5 litre container. You can use sodium bicarbonate too, but I do not like doing that because it seems to create peculiar flavours because Na is very low in coffee beans.
An easy way to make it up is to make a bottle of concentrate: Get a 750 ml stoppered bottle, add 9.6 gram of potassium bicarb to that, fill with water and shake well. Then for every US gallon of purified water just add 1 to 2 tablespoons of that concentrate. (1 tablespoon works out to 0.5 mMolar bicarbonate -- or a total alkalinity bump of 25 mg/L as CaCO3.) If you go with sodium bicarbonate (baking soda) you would use a little less - about 8.1 g instead of 9.6 g in the concentrate bottle.
If you used distilled or the non-mineral version of Nestle Pure Life it should be best because of having zero chloride, but this recipe would nicely fix the low alkalinity in the water you already have.