Blimey, Severn Trent reports really are rubbish. I think the first ST reports I got were okay ... "beginners' luck"? Got this out, but the exercise confirmed why I need to continue developing that "Defuddler" spreadsheet ... I had to use some tricks I hadn't originally anticipated:
The grey boxes just indicates where the "Foetid Mire" (all the "Hardness" toss, "CaCO3", etc.) has had to be used to drag out a value. You can expect to rely on the "Mire" for one or two values (because few have decent water reports from the UK water companies), but three is the maximum! I'll tell you the assumptions I had to make (and that I'll need to manage better in that "Defuddler").
What follows is an explanation for geeks.
You do not need to know any of this stuff! That's what the "Defuddler" attempts to guide you through! I include it only to be transparent about what I'm doing!
We need "Total Hardness", an otherwise useless measure but we can scratch something out of it. Severn Trent don't provide it! But they do provide "French Hardness". Multiple by ten and we have "Total Hardness" measured "as CaCO
3". Flippin' "CaCO
3"; well, you know what I think of that! And it's about to get worse!
"Total Hardness" is the sum of Calcium and
Magnesium (and other multi-valent metal ions, but they amount to near nothing in drinking water - that's lucky!!!). But "Hardness" provides no way to determine how much Calcium and how much Magnesium ... sooooo, we guess! Fortunately, unless you know you're in a high Magnesium area, its fairly reasonable to guess as a 9:1 split (the "9" being calcium).
Next, we come to "Bicarbonate". It is always bicarbonate unless you have very alkaline drinking water (above pH8.5) when there might be a smidge of "carbonate" (but not after the water is treated for brewing). You
cannot use the "Total Hardness" figure to work out alkalinity. "Temporary Hardness" you can (even "Permanent Hardness" with total hardness if you're in the know), but not "Total hardness" on its own. The "Defuddler" is using another assumption in this case. The dissolved solids in drinking water will be due almost entirely from the first five ions in the screen clip. Everything else amount to almost nothing, except perhaps "nitrates" and "phosphates" which are included as "miscellaneous" ions in the screen shot. So, adding up the five "known" ions and balancing the positive results ("cations") and negative results ("anions") leaves a gap that can be assumed as "bicarbonate" "anions".
All six boxes filled; job done! Phew! It's usually easier but ST are particularly painful.
Information gathered in this manner (from the "Mire") must be
manually inserted into the six boxes at the top to avoid entering dud values. The six values should work as-is in any decent calculator. Ignore any request for "Hardness" values (other than mentioned above). If the calculator won't work with the six discovered values ... get a better calculator!!
How I stop people messing about with these figures in the "Mire" when they don't need to is beyond me. Please, please, try not to be one of those people! The "Defuddler" tries to
save you from all the twaddle I've just described ... it's
NOT trying to teach you it!
