First of all, your water's 9.65 pH is rather high (i.e. very alkaline) already and, since a decarbonizing filter would be used to raise the pH of acidic water, you have absolutely no need for one. If it did anything to the already high pH, which I think is doubtful, it would make it even higher, which could be problematic.

There is a popular notion that drinking alkaline water with pH in the 8.5+ range is "better for you," but the jury is still out on that. It's a bit more clear that slightly alkaline water (e.g. pH 7.5-8.0) is better for your espresso machine than acidic water (pH < 7.0) as regards corrosion risk. Furthermore, high alkalinity correlates with higher concentration of dissolved solids that in itself can promote limescale.

In short, you definitely don't need a decarbonizing filter and if anything a filter that might slightly lower the pH would be something to consider.

achosid wrote: I was able to test my pH at home: 9.65. Does this alter your recommendation as to whether I should stick with conventional softening or consider a decarbonization tactic?

I think Pressino got it backwards above. A decarbonizing filter traps hardness ions and releases H⁺ ions, so it tends to lower the pH.

In some cases, especially with low alkalinity water, the pH can easily drop below 7 and the acidic water combined with the chloride ion can become a corrosion issue.

High pH usually indicates a high alkalinity. But this is not always the case. Water treatment utilities sometimes use chemical treatments that can raise the pH without increasing the alkalinity. The water in the distribution system will have a high pH, with much lower than normal CO2 and carbonic acid content, and be less corrosive to the pipes. But that pH will slowly drop after the water is out and exposed to atmospheric CO2. Your Ward labs number for alkalinity and carbonates indicate an alkalinity much lower than would be expected for a water with your high pH.

It's a judgement call, but I'd still argue against a decarbonizing filter. There is some nice technical guidance from Pentair related to that here: /downloads/ ... pdated.pdf

The punchline in that article would be:

Claris (like other WAC products) is great for water with bicarbonate levels above
100 & low chloride and sulfate levels less than 80ppm and 150ppm respectively.

Your bicarbonate/alkalinity is way below 100 ppm your chloride is about 30, so I think this advice does not advise a decarbonizer (WAC resin ion exchange). Be aware that Pentair sells a very popular decarbonizer (the Everpure Claris) and that this advice is for stainless steel. My understanding is that copper and brass is more susceptible to chloride corrosion risks.

Another downside for you is that decarbonizers typically require an alkalinity (KH, carbonate hardness) measurement to get the bypass settings right. If you go that route I think you'll want to have an alkalinity drop titration kit on hand that you can use, perhaps with some assistance on the color detection.

homeburrero wrote:Your Ward labs number for alkalinity and carbonates indicate an alkalinity much lower than would be expected for a water with your high pH.

I think I'm going to do another Ward Lab test to see: the other test was old and from another house. Am I correct that the data I had on the previous report is sufficient? They offer a variety of different tests for different water components:

https://www.wardlab.com/submit-a-sample/water-analysis/

The Brewer's Test resulted in the previous report.

achosid wrote:I think I'm going to do another Ward Lab test to see: the other test was old and from another house. Am I correct that the data I had on the previous report is sufficient? They offer a variety of different tests for different water components:

The W-501 (brewers' test) and the W-5 (household complete mineral test) list the same 17 analyses and cost the same, so I see no reason to choose one over the other.

Your report looks more than sufficient. In some places with volcanic water sources the silica number may be worth knowing but not St Louis.

homeburrero wrote:I think Pressino got it backwards above. A decarbonizing filter traps hardness ions and releases H⁺ ions, so it tends to lower the pH.

oops! my bad. probably needed more coffee before I posted that...and should have said that a decarbonizing filter would be a quite reasonable option, with need for follow-up pH measurement while adjusting the filter bypass. thanks for the correction.

Plug the numbers into LaMarzocco water calculator

Neat little page


https://techcenter.lamarzocco.com/en/watercalculator