Greetings all! I am trying to assess the need for additional filtration requirements for my city water supply. I am presently using a filtration system to remove heavy metals, fluoride, chlorine and chloramines.

The city of Minneapolis has what I believe is considered an excellent water treatment process. I am just not sure how that relates to scale in a boiler. Attached are links to the latest annual water report and the most current monthly report.

I am having difficulty interpreting the city water reports. I understand the information in theory, however in the big picture, I get a little lost. I am interested in minimizing the need for descaling and devising a plan to keep the boilers of my machine clean and healthy. Thank you for any input you may offer.

September 2018 water report
http://www.ci.minneapolis.mn.us/www/gro ... 214719.pdf

2017 Annual water report
http://www.ci.minneapolis.mn.us/www/gro ... 209178.pdf

Craig <SeaRizz>

Those water reports are excellent. And the water ain't bad either.

Summarizing some key numbers:

total alkalinity (ppm as CaCO3) 26 - 63 (43 avg)
total hardness (ppm as CaCO3) 61 - 110 (82 avg)
calcium ion (ppm) 23.1 - 36.9 (29.3 avg)
chloride ion ppm 22.7 - 29.9 (26.8 avg)
sulfate ion ppm 23.7 - 34.1 (27.7 avg)
silica (ppm as SiO2) 6.4 - 11.5 (8.7 avg)
TDS (dry residue ppm) 135 - 204 (167 avg)
pH 8.25 - 9.24 (9.03 avg)

From the calcium number you simply multiply bu 2.5 to get:
calcium hardness (ppm as CaCO3) 57.7 - 92.3 (73.3 avg)

They didn't provide a conductivity measure, so can't calculate how a TDS meter would read.

The pH coming out of the plant is high (usually is, due to treatment) but should equilibrate after exposure to air and absorbing CO2 to make carbonic acid. With an alkalinity of 43 the equilibrium pH (for use in scaling calculations) would be around 6.9

The chloride is higher than what one manufacturer recommends (Synesso likes chloride to be below 15ppm) but isn't bad as long as you keep that alkalinity. Your chloride is below the 30 - 50 ppm that La Marzocco recommends (http://www.lamarzoccousa.com/wp-content ... ations.pdf. and https://au.lamarzoccohome.com/wp-conten ... er-Doc.pdf)

If you run these numbers through the La Marzocco water calculator (https://techcenter.lamarzocco.com/jsp/T ... ulator.jsp), it will say that all you need here is a particulate and carbon (taste, odor, chlorine) filter.

Your alkalinity and hardness numbers put you slightly on the hard side, but close enough to ideal zones from the old SCAA recommendation as well as the newer SCA core zone (see Good references on water treatment for coffee/espresso )

At steam boiler temps, slight scaling can be expected from this water. Your Langelier Saturation Index, at equilibrium pH and 125C is about 0.2, indicating that the water should tend to deposit rather than dissolve calcium carbonate scale. But that number indicates low scaling potential. (For more on this calculation, refer to the Jim Schulman Insanely Long Water FAQ.)

You could soften this water if you wanted to assure that you'd never need to descale. But if you do that it's probably wise in this case to stick with conventional softening (sodium or potassium ion exchange) and avoid the decarbonizing filter (aka WAC filter, aka H+ exchange filter, aka carbonate hardness filter) that is now widely available from BWT and others. A decarbonizing filter would reduce your alkalinity, and you don't want to do that with this water because the alkalinity is not very high and you have that 20-30 ppm chloride.

Thanks for helping to cut through some of the confusion. I came to a similar conclusion albeit from a less objective perspective. The number that stands out for me is the pH. From what you are saying that is not an issue an should normalize. This I would have never known.

Ill check out the links you provided. Thank you for that. I really appreciate your insight!