Water Reports - Nitrates & Phosphates

[PeeBee]

I only noticed today that Dwr Cymru had published our water quality report for 2023. As in recent years, more than just the ion, etc. amounts had changed, the format changes too.

There was one very notable change. They've started reporting "nitrates" as "N". America have been doing it for some time with their "NO3-N" reporting. It's claimed horticulturists and agriculturists want it like this, but I reckon they just do anything to hide embarrassingly big numbers for "nitrates" (mostly due to pollution). But, in Wales, the NO3 figures are quites small (2.6mg/L for me). Anyone notice other UK water companies using "N" for reporting?

Covert "N" back to "Nitrate" by multiplying by 4.4266. Just like the Americans have to do with "NO3-N".



Dwr Cymru have been reporting "Phosphates" as "P" or "Phosphorus" for some time. That doesn't bother me because I calculate Alkalinity and phosphate is on the "alkalinity" side of the equation. Convert "P" to "Phosphate", more indication of pollution, (assume P2O5) by multiplying by 2.2951. The other compound that can be reported this way is sulphate as "SO4-S" (multiply "sulphur", "S" or "SO4-S" by a nice round "3" to get "sulphate", but I don't think we'll be seeing that 'cos "sulphate" isn't an embarrassment!).

[PeeBee]

I've stated above "I calculate Alkalinity". This is not the normal for home brewers. I don't know why? It makes things so much easier, but homebrewers prefer to have their heads in the sand? The "equation" (it's hardly that!) is:

"TA" or Total Alkalinity = ∑conservative-cations - ∑conservative-anions

"Conservative" in this context effectively means "NOT Alkalinity". Which "effectively" makes the above equation for Total Alkalinity "stating the flippin' obvious" (think about it!). i.e. "TA" = ∑(NON-conservative-anions). In drinking water "NON-conservative anions" are "carbonate" (rare!), "bicarbonate", "phosphate", "hydroxide" (rare) and "silicate" (insignificant). More complete lists (stuff not found in drinking water!) can be found elsewhere (e.g. https://en.wikipedia.org/wiki/Alkalinity?).

Of the "rare" ones:

Tap water is normally at a pH lower than 8.3 … "carbonate" begins to replace "bicarbonate" as the normal alkalinity species ("stuff") in tap water at pH above 8.3; and visa versa.

"Hydroxide" in the form of "slaked lime" (often abbreviated, incorrectly, to just "Lime", or else; "calcium hydroxide", or "Ca(OH)2 ) is some times added (dosed) to acidic waters by the water companies (e.g. surface runoff water from peat land). Hydroxide reacts with other compounds, like carbon dioxide to create more carbonate or bicarbonate.

[PeeBee]

A query was raised outside this thread as to why "phosphate" is included as an alkalinity contributor and not among the "conservative" anions. Answer: Search me! But "Phosphate Alkalinity" is a "thing" (look it up). "Phosphate" is not a "Conservative Ion". Therefore, whatever "phosphate" is up to (and silicate too?), it's not counted amongst "conservative ions" and that leaves "total alkalinity" to account for its existence (something we can just accept without knowing the fine detail).

If anyone has a simple explanation, do post it!

You'd be unfortunate if your water had enough phosphate (pollution remember) to make a radical difference. I'm happy to have an excuse to ignore it in brewing water calculations.

[PeeBee]

From Google (some sort of new information collecting AI that leaves you puzzling where the reference(s) comes from! I searched for "Phosphate alkalinity in water"):

The advantage of having people question me is that finding stuff reinforces what I thought I knew, which helps everyone because afterall, who is going to believe a brain-damaged loony. The disadvantage is it takes me forever digging this babble out of its hiding place!

[PeeBee]

Something else I noticed in the above prattling: "I'm happy to have an excuse to ignore it [phosphate] in brewing water calculations".

You can't do that! You can, because "bicarbonate", or if still with the arcane stuff measured as "calcium carbonate" ("CaCO3"), is an "equivalent" too, and any significant phosphate alkalinity will be wrapped up "as bicarbonate" (aka: "Total Alkalinity", or is that stretching it too far?), or whatever arcane measure you use. So ... Ignore it!

There's enough pharting about in this game without grubbing about in the slime to find more.


[EDIT: The other minor point that came out of that Google AI clip: "Borates" ... they appear to be limited to sea and brackish water. I was surprised to see "silicates" in a water report in notable amounts, which I consider as ">1ppm", but "there" it was! They are both collected under the "Total Alkalinity" umbrella, so I ignore them too.]