Tough times with water report

[Arska]

So.. I found water report of my home town and need a little help with it.

Sulfate: 8,6 ppm
Chloride: 4,0 ppm
Sodium: 3,1 ppm
PH: 7,5
alkalinity: 0,9mmol/l
hardness: 3,1'dh

How do I get my Ca, Mg, bicarbonates and alkalinity as ppm?

I finded that if U multiply: dh x 17,9 = ppm (is that true?)
And that water hardness is calculated: In 1'dh there's 10mg/l of Ca.

 

[ajdelange]

Yes, 17.848*dh gives ppm as CaCO3 so your hardness is 55.3 ppm as CaCO3. From the data you have you cannot tell how much of that is attributable to calcium and how much to magnesium - only that the sum is 55.3. So calcium hardness of 35 and magnesium hardness of 20.3 is a possibility but so is 55 calcium hardness and 0.3 magnesium hardness as are many other combinations. It is likely that there is somewhat more calcium hardness than magnesium hardness but this is not always the case. So you have to make a guess as to how the two are distributed. 35.3/20 is probably a reasonable guess. Calcium ion concentration is found by dividing the calcium hardness by 50 and multiplying by 20 so 35.3 ppm as CaCO3 translates to 23.4 mg/L and magnesium concentration is found by dividing the magnesium hardness by 50 and multiplying by 12.15 thus 20 ppm as CaCO3 is equivalent to 4.86 mg/L magnesium ion.

Alkalinity is usually expressed in terms of the number of milliequivalents/L required to neutralize all the bicarbonate ions in the water (i.e. convert them to CO2) or 50 times that which puts the alkalinity in ppm as CaCO3 for direct comparison with hardness numbers. As such it is approximately equal to the number of mEq/L bicarbonate ion which, as bicarbonate ion is singly charged, is equal to the number of mmol/L bicarbonate. Assuming that this is the case here then it is only necessary to multiply 0.9 by 50 which gives alkalinity equal to 45 ppm as CaCO3. To obtain bicarbonate multiply by the molecular weight of bicarbonate which is 61 i.e. 0.9*61 = 54.9 mg/L bicarbonate.

 

[Arska]

Thanks for helping. I was a bit confused with all those mmol/l and dh:s. I'll send e-mail to the local water department about those missing minerals.