Hello All

I was looking for a inline water softener (hard Calgary water) for the 2005 Bezzera BZ40 I just got. I came across this statement on espresso planet with their BWT filters.
"Not for use with machines that have components made from copper, galvanised, chromium-plated or nickel-plated material." (https://www.espressoplanet.com/BWT-Best ... stems.html)
Is this a real concern?
I don't see warnings all over the place on forums so I am assuming that it isn't. Anyone have any insights?

Additionally here is my city's water tests. Anyone have a filter recommendation?
https://www.calgary.ca/UEP/Water/Docume ... y-2018.pdf

Thanks
J

I looked at the BWT site and see no mention of this issue. I also contacted WLL and they replied that they know of no issues with copper. I've emailed BWT but have not heard back yet.

I can't imagine that there is an issue as most all espresso machines have some copper and many of the big retailers sell this (WLL, Prima, Voltage...). I'll report back when I get a definitive answer.

BWT BestMax filters employ weak acid cation media as one stage which lowers the pH of water. Calcium will not precipitate out (cause scale build up) in low pH water. When the buffering component of the filter assembly is exhausted, the pH can drop rather dramatically. Copper is susceptible to corrosion in low pH environments - https://www.plumbingsupply.com/cuinfo.html. Use with caution and test the pH of your water after the filter.

I agree with Scott (Ciaran) that the Espressoplanet caution is based on the fact that this filter is primarily a Weak Acid Cation (WAC) resin. FWIW I'll add more info and opinion and hopefully address your general question:

jpaul wrote:Additionally here is my city's water tests. Anyone have a filter recommendation?
https://www.calgary.ca/UEP/Water/Docume ... y-2018.pdf

WAC is different from conventional softening resins because it exchanges two hydrogen ions (H⁺) for each calcium (Ca²⁺) or magnesium (Mg²⁺). Another name for this is a decarbonizing filter or a hydrogen ion exchange filter. Since they release H⁺ into the water, the pH drops. In natural water with some carbonate alkalinity, the H+ is buffered to form carbonic acid (H₂CO₃), which decomposes to CO₂ and H₂O. When the dissolved CO₂ is released as a gas, the pH tends to return to the equilibrium pH that corresponds to the alkalinity of the water. Decarbonizing filters are effective in reducing limescale because they 1) reduce the pH, 2) reduce the calcium ion, and 3) reduce the carbonate/bicarbonate. All three of those are a factor in whether and how much limescale might deposit in the machine.

The lower pH and the lower alkalinity after decarbonizing is a major concern with these filters, although I think it's overstated and oversimplified by Espressoplanet's cautionary statement. There is some good information related to that on this forum at the thread: Warning: Chloride & sulfate levels with weak acid cation softeners (e.g., Everpure Claris) and in a nice presentation from Pentair here: /downloads/ ... pdated.pdf . The Pentair discussion is focused on stainless steel corrosion, but the effect of acids and chlorides would be even more of a concern for brass and copper. There is also some good information related to decarbonizing filters in the 2018 SCA Water Quality Handbook, including a graph indicating the initial drop in pH relative to the reduction in alkalinity.

Many popular home espresso filters and most of the BWT filters use decarbonizing (WAC) resins. Most of them are used with an adjustable bypass head so that you can dial it up so that the water comes out with reasonable alkalinity. They often come with a KH test kit or strip which you use to test your tap water and decide where to set the bypass dial. There is one BWT filter (BWT Betsprotect) that uses a conventional softening resin (Strong Acid Cation) that replaces calcium with sodium ions. (Note that the Espressoplanet verbiage on that one https://www.espressoplanet.com/BWT-Best ... stems.html says: "Bestprotect filter cartridges are recommended for use for machines susceptible to corrosion.")

For your Calgary water, given your low chloride (3.6 - 5.9 mg/L) and above 100 mg/L alkalinity I think you can do fine with a WAC resin and a high bypass. Your alkalinity is at 118 mg/L or 6.6 °dKH, your total hardness is 168 mg/L or 9.4 °dH, and your calcium hardness works out to 100 mg/L - so if you dial it to keep around 50 mg/L of alkalinity, that would give you ballpark of 71 mg/L total hardness, 42 mg/L calcium hardness (all in units of CaCO₃ equivalent, of course.) So I think you should have little or no limescale, and have minerals close to what conventional wisdom recommends for tasty coffee. The pH may be a little low coming out of the filter, but not unreasonably because of the high bypass. (The SCA handbook advice recommends that you not use a decarbonizer to drop the alkalinity more than 200 mg/L, and your reduction will be well below that.)

The BWT Bestmax seems the most predictable and I'm not that sold on the need here for the Bestmax Premium. Both would tend to reduce alkalinity and total hardness by about the same amount, but the Premium would reduce calcium hardness slightly more than magnesium hardness. This may have a taste advantage (unproven) and might tend to further reduce your potential for limescale and for hard to remove calcium sulfate (gypsum) deposits.

Your other option for Calgary, and one that I'd probably use, would be to just use a conventional softener. This would keep your alkalinity (and pH) the same and drastically reduce the hardness minerals to scale-free levels for both limescale and calcium sulfate. If you used a sodium-based softener it would increase your sodium, but even if you softened down to zero hardness it would only add about 37 mg/L of Na⁺ ion - not enough to worry about in my opinion. You could use a combination cartridge like the BWT Bestprotect, or combine an inexpensive 10" cartridge softener or a rechargeable canister salt softener along with a separate charcoal block filter (for particles, chlorine, taste, odor). Your 118 mg/L alkalinity would be higher than usually recommended as a coffee brewing ideal, which per conventional wisdom might dull the acids in a cupping or pourover brew situation, but for espresso taste I think moderately high alkalinity is a non-issue - there's just not enough water in an espresso to make much difference.