According to La Marzocco specs (PDF) the Recommended Total Hardness range is 70 to 100 ppm. Does anyone know the rationale behind this recommendation? Is it related to impact on taste or reliability?

I'm using RPavlis water which is well below that range. Should I consider adding hardness (e.g. Epsom salt) to increase hardness so that it fits into this range?

Yes, I would (and did) for my LMLM a couple years ago. I had a minor issue with the machine and the first question I was asked by service folks at LM and Chris's was about the water I was using. Both entities were adamant that I needed to use properly buffered and remineralized water for the health of the machine and to bring out the best taste in the beans.

boren wrote:According to La Marzocco specs (PDF) the Recommended Total Hardness range is 70 to 100 ppm. Does anyone know the rationale behind this recommendation? Is it related to impact on taste or reliability?

Excellent question. With water at the hard end of that recommendation you would need to be vigilant about descaling. I noticed that their April 2022 online advice allows for the use of softer water: "La Marzocco's water guidelines can be used to compare with local water test results. Some bottled water recommendations are softer than this, but are still safe to use."

That page also implies that they believe in the idea of protective scale for espresso machines: "In normal, small amounts, scale actually helps protect metal in the machine." I would be curious to learn how La Marzocco shops like Caffe Vita in Seattle or Portland treat tap water that is far softer than this recommendation.

boren wrote:I'm using RPavlis water which is well below that range. Should I consider adding hardness (e.g. Epsom salt) to increase hardness so that it fits into this range?

I think you could do that in case it might improve taste (many think that it will). But it won't do anything to add limescale deposits. Many of us, including Dr Pavlis, don't agree with the idea that limescale is protective. It is porous and is not deposited uniformly on metal surfaces, and if it is accumulating you will need to descale the machine. Descaling solutions are corrosive to metal and can remove oxide layers that are thin, uniform, and actually are protective.

FWIW, here's an image that shows their hardness and alkalinity range alongside some other recommendations:


The underlying chart and discussion is from a 2016 posting here: Good references on water treatment for coffee/espresso

First off, I am not a chemistry expert. I am also not an espresso expert by any means.

But having recently ordered a Micra, I had a little "back and forth" with La Marzocco on this subject. When discussing their guidelines and bottled water recommendations. I had come across this 2021 Poland Spring Water report:
https://www.google.com/url?sa=t&source= ... 1KNj1YqU1h

Compared with La Marzocco's guidelines, this report shows a range of numbers far softer than their guideline range. Their reply was "Poland Spring spring water is bottled in Maine, and is very consistent. It's our favorite in terms of bottled options." Upon further discussion I was told "Since water related issues are not covered under our warranty, I encourage you to use one of the tried and true bottled water recommendations." With Poland Spring Water being the only available bottled option for me. They had another option to use TWW Espresso profile. Maybe they aren't as strongly committed to their "hard water" guidelines.

My biggest issue is my trust in Poland Spring water in regards to consistancy in its numbers, in particular, the chlorides. I tested a 2.5 gallon from a local store myself and all the numbers match. Only issue is I'm waiting on the chloride results as I don't have a way to test for it presently.

boren wrote:According to La Marzocco specs (PDF) the Recommended Total Hardness range is 70 to 100 ppm. Does anyone know the rationale behind this recommendation? Is it related to impact on taste or reliability?

I'm using RPavlis water which is well below that range. Should I consider adding hardness (e.g. Epsom salt) to increase hardness so that it fits into this range?

After running my well water (327ppm TDS) through an RO system, I have a TDS of 20ppm. If I then run it through a BWT Penguin pitcher I end up with a reading of 73ppm due to the added magnesium.
This is for my espresso machine.

For drinking water, I will drink the RO water and once per day remineralize a quart using LMNT.