The SCAE funded report is out now, and you can download it freely -- no SCAE membership required:

http://scae.com/images/pdfs/SCAE-water-chart-report.pdf *

Congrats to Marco Wellinger (HB member welone) and co-authors Samo Smrke and Chahan Yeretzian on a job well done!

Much of the discussion focuses on hardness and alkalinity, and does a thorough job of it. On page 8 there is a handy chart with all the standard unit conversions (gpg, °f, °d, ppm as CaCO₃, etc) in one place.

* Edit addition, Dec 2016. That link finally went dead, and you now need to be an SCAE member to get access to the report. (start here) Was nice while it lasted!

Fantastic find! I can't wait to dive in!

Today I noticed some changes in some facebook announcements and links about this report, and I wonder if they did intend it to be available free to non-members. At the moment you can still download via the link above, but if you browse the info on the SCAE site:
http://scae.com/tools-and-resources/research, as a non-member you will not find a link to download the PDF. As with other SCAE research reports, I suspect this paper may be intended to be freely available only to SCAE members:

... Use the links in the left hand menu to read more about the research reports. SCAE Members can log-in and download the research papers ...

Since it's SCAE funded, it makes sense to restrict it to members, but if they do that I hope they find a way to sell it to non-members, as was done with the 2011 SCAA Water Quality Handbook.

Can anyone weigh-in on how they calculated the line in Figure 6: Corrosion risk zones that corresponds to a value of ~0.8 for the S1 Corrosion Index?

The DIN 12502 spec that they reference defines S1 in terms of the concentrations of chloride, sulfate, nitrate & bicarbonate ions. It's not clear to me how they extrapolated the total hardness limits from that equation that were used to calculate the corrosion boundary, which defines one side of their recommended "Core zone" (Figure 8, p. 12 &13).

Close inspection of these figures shows that the Larrson-Skold Index at 0.8 line in Fig. 6 would actually bisect the "Core zone" as it is displayed in Fig. 8, effectively cutting the zone in half. Careful measurement shows that the slope & intercept of this boundary in slightly different in each of these plots (Fig. 6, Fig. 8 on p.12 & Fig. 8 on p.13).

From Tamper Tantrum:

Attention, water geeks! This week's video is for you. Dr. Marco Wellinger, leading author on the SCAE's recently published "The SCAE Water Chart: Measure, Aim, Treat", took to the stage in Antwerp to share the most-recent results of his then ongoing research in preparation for publication. Dr. Wellinger's talk is a deep dive into some of the water conundrums he and the SCAE Research team faced when developing the water chart, like the fact that pH measurements are often a poor indicator of a water's alkalinity and why you sometimes get "fizzy espresso" after treating very hard water with decarbonizing ion-exchangers. This is definitely another talk where you'll want to have a notebook, pencil, and the ability to hit a pause button as you watch!

You can view it here: http://www.tampertantrum.com/water-for- ... xtraction/

bdswan wrote:Can anyone weigh-in on how they calculated the line in Figure 6: Corrosion risk zones that corresponds to a value of ~0.8 for the S1 Corrosion Index?

The DIN 12502 spec that they reference defines S1 in terms of the concentrations of chloride, sulfate, nitrate & bicarbonate ions. It's not clear to me how they extrapolated the total hardness limits from that equation that were used to calculate the corrosion boundary, which defines one side of their recommended "Core zone" (Figure 8, p. 12 &13).

Close inspection of these figures shows that the Larrson-Skold Index at 0.8 line in Fig. 6 would actually bisect the "Core zone" as it is displayed in Fig. 8, effectively cutting the zone in half. Careful measurement shows that the slope & intercept of this boundary in slightly different in each of these plots (Fig. 6, Fig. 8 on p.12 & Fig. 8 on p.13).

I noticed some of that also, and perhaps Marco Wellinger (welone) will give an authoritative reply, but FWIW, I'll give my interpretation of it:

The difference between figs 6 and 8 on pg 12 look like a simple slip in the graphic for fig 8. Note that the ticks and labels on the x axis (alkalinity) are not aligned, and that the "SCAA standard" line appears to have shifted down below the 40ppm alkalinity where it belongs. To my eyes, fig 6 looks fine - hard to tell because it's scaled differently (shows alkalinity out to 300 ppm.)

The dashed line on fig 6 labeled "Larson-Skold Index at 0.8" goes from the origin through the (150,250) point, so is clearly hardness = 5/3 * alkalinity. I think that line would describe a Larson-Skold Index of 0.67 under the simplifying assumption that all the non-carbonate hardness is due to chloride and sulfate, and that there is no chloride or sulfate other than that associated with Mg and Ca. They may have some other assumption for calling it an index of 0.8.

I think the core zone on figure 8 pg 13 is the one to use - partly because it's scaled big enough to see clearly. If you draw a 'hardness = 5/3 * alkalinity" line on that one, you will see this:

And as you say, that line does bisect the zone. But the upper limit of the zone does follow the slope of that line so I just assumed that they chose their upper limit based on about 10ppm hardness above that line.

Hi there
I'm glad you guys are taking the chart under close inspection - I'm currently on vacation so I only have limited online access..
I agree completely with homeburreros explanations - with a very minor difference, that is that as an approximation we suggest that total hardness should not exceed 1.8times alkalinity (instead of tot.h. = 5/3* alk = 1.67 * alk). Unfortunately some of the graphs were distorted during final layout - though I certainly cannot complain about it sice it all happened within a few days only..
And yes as a reference figure 8 on page 13 is the most useful because it is large enough and not distorted.
Here is the relevant part about the core zone regarding corrosion:

The horizontally striped zone marks
too high chloride or sulphates concentrations corresponding to a Larson-Skold-Index above 0.8. Although the index is estimated from total hardness and alkalinity alone it yields a practically useful result unless
high concentrations of sodium are present (introduced with sodium hydrogen carbonate). A more general
rule that also encompasses waters with a signifcant amount of salt (other than calcium or magnesium carbonate) has been established based on the data from Lockhart (1955) and 23 waters from the region of Barcelona (representative of salt water in uenced tap waters). To keep the risk of corrosion low, the electrical conductivity (in μS/cm) at 20°C should be no more than three times the alkalinity (in ppm CaCO3). A ratio of three to one, of electrical conductivity to alkalinity, corresponds to a value of approx. 0.8 of the S1 corrosion index (DIN 12502). The S1 corrosion index is almost identical to the Larson-Skold index but additionally also takes into account the concentration of nitrates (in addition to chloride and sulphate).

If anyone is interested in the raw data mentioned (Lockhart and Barcelona waters) I'd be glad to share them via email.
Greets from San Sebastian
Marco

Since around December 2016, we've been unable to get a copy of the SCAE water chart without buying an SCA membership. And the SCA provided no way to just buy the report outright.

I think that may have just changed - starting today you can buy a new SCA water handbook: https://store.sca.coffee/collections/bo ... 9334327398

45 bucks, purportedly draws on the SCAE water chart work, although it doesn't say much -- not even a mention of how many pages. My copy is on order, will let you know more after it comes in. I think that anyone at the Seattle Expo may be able to snag a copy there.

P.S.
The other place where you can get much of this info is in Chapter 16 of the Craft and Science of Coffee book. https://www.sciencedirect.com/science/a ... 5207000165 . Same authors, 17 pages. (The SCAE Water Chart is 33 pages.)