Unbalanced Water Report

I had Ward Labs run a test of my "unsoftened" drinking water from my well in CT. I was inputting the lab results into the Bru'N Water Spreadsheet and it flags a warning that my water is unbalanced, but I can't find any info on what it means or possible corrections. A chemist I am not, so I need some help in interpreting the results and if there is any hope of using my water to brew with.

David




pH 7.2
Total Dissolved Solids (TDS) Est, ppm 942
Electrical Conductivity, mmho/cm 1.57
Cations / Anions, me/L 14.8 / 13.5

ppm
Sodium, Na 14
Calcium, Ca 182
Magnesium, Mg 30
Total Hardness, CaCO3 580
Nitrate, NO3-N 1.9 (SAFE)
Sulfate, SO4-S 9
Chloride, Cl 413
Carbonate, CO3 < 1
Bicarbonate, HCO3 60
Total Alkalinity, CaCO3 49
Total Phosphorus, P 0.55
Total Iron, Fe < 0.01
"<" - Not Detected / Below Detection Limit

The imbalance refers to the line in the report.

Cations / Anions, me/L 14.8 / 13.5

Water is electrically neutral. It is impossible for a water sample to have a charge of + 14.8 mEq/L from cations and -13.5 mEq/L from the anions as this results in a net charge of +1.5 mEq/L. That means that these charge numbers, obtained by adding up all the plus charges from the individual items in the report and doing the same for the negative charges are in error. They may be in error because some charged species was not measured, because an error or errors were made in individual measurements or because of calculation errors. We have confirmed that Ward Labs makes calculation errors by checking the ratio of reported carbonate to bicarbonate concentration in reports for water samples at higher pH. And we can assume that there are some measurement errors because there always are.

Your real question is, of course, 'what can I do about this?'. The answer is nothing. If you are trying to synthesize a profile the profile must be balanced, as must indeed all water compositions, and you will find that you cannot build a balanced profile from an unbalanced report. You will have to balance it by guessing as to how much calcium was over stated or bicarbonate understated. You have to W.A.G. additions to the anion side and/or decrements to the cation side until you get balance (or close to it). As few people try to match profiles any more you will, in most cases, simply ignore the imbalance signal and move on.

Ignore the imbalance signal and move on I can do. If there are errors or non measured charged species it makes one wonder about the accuracy of the overall report in general.

For the money Ward Labs reports are pretty good. Unmeasured stuff is not likely to contribute much to the error. A bit from iron, a bit from manganese, a bit from strontium, a bit from aluminum, a bit from nitrite... Run some reasonable numbers for these and you'll see they don't amount to much. The errors bicarbonate and carbonate are the result of a common practice in the water industry and that is because not all waters that are analyzed are potable. One can calculate bicarbonate and carbonate accurately from alkalinity (what they actually measure) only if carbonate/bicarbonate is the only buffer which it should be in potable water but as you can see from your case there is some phosphate present so even the 'correct' method of calculation would be in error because of the phosphate unless the calculation were made more complex to account for that.

Flynz said:

Ignore the imbalance signal and move on I can do. If there are errors or non measured charged species it makes one wonder about the accuracy of the overall report in general.

Click to expand...

The suite of ions that Ward tests for represents the typical ions found in most water supplies. There are places that have a few more ions that may not have been tested for. An important one is silicate and its concentration can be somewhat high in some waters.

AJ's points are valid. For the most part, I've seen Ward reports as reasonably accurate. The apparent lack of ionic balance is a red flag, but only to a degree (orange flag?). The imbalance could be a product of the condition I mention above, but it could also be a lab or reporting error. That red flag is an alert to the brewer that a second look at the testing and reporting is prudent. Possibly resample the water and retest to confirm the original result. If it also comes back unbalanced, you can assume that there is a significant concentration of ions that exist in that water that were not tested for. Knowing what those ions are, would be nice. But they are probably not critical to successful brewing (as long as they don't contribute to off flavors).

mabrungard said:

An important one is silicate and its concentration can be somewhat high in some waters.

Click to expand...

I've never been able to convince myself that silica is responsible. I believe the range is generally 1 - 30 mg/L as SiO2 (though I'm sure in unusual cases it can go above this). I happen to be fortunate (that's sarcasm) to have 28 mg/L. Call it 30. As the molecular weight of SiO2 is 60 that would give me 1 mEq/L negative charge from H2(SiO4)-- if the silicic acid deprotonated twice. But that takes pretty high pH. The first pK is 9.5 and the second 12.6. Thus at pH 12.6 the theoretical charge would be -0.75, and at 9.5 it would be -0.5. At more typical pH's, like the OP's 7.2, it is going to be much less than that (-0.002 mEq/L at 7.2).

Not that it can't be a pain in other ways. It has never gummed up an RO system of mine though I run at lower recovery than I would have to if I didn't have so much.

I appreciate the responses to my post. A bit over my head at times, but nothing that I should be too concerned about regarding the overall quality of my water.

I'll continue on to learn about my water and how it relates to brewing using the online calculators. Thanks for your valued time.

David