Water Report for Eagan, MN

[KeninMN]

This is the information I received from my city water department, in answer to a direct request:

Alkalinity/Bicarbonate = 270 mg/L
Alkalinity/Carbonate = 1.3 mg/L
Ph = 7.6 mg/L
Calcium = 170 mg/L
Dissolved Oxygen = 10.34 mg/L
Iron = ≤ 28 ug/L
Manganese = ≤ 10 ug/L
Mg as CaC03 = 110 mg/L
Nitrate & Nitrite Nitrogen, Total = ≤.05 mg/L
Nitrate Nitrogen, Total = ≤.01 mg/L
Oxidation Reduction Potential (O.R.P) mV = 577.2
Phosphate = .042 mg/L
Total Organic Carbon (TOC) = ≤1

This is what they published on their Web site:

http://www.cityofeagan.com/index.php/communications/newsletters-publications/2012-12-19-14-55-19/drinking-water-quality-report/beer-brewing-water

The Critical Seven

Alkalinity, Carbonate (CO3)........................... 1.3 to 1.7 mg/L

Alkalinity, Bicarbonate (HCO3)............................... 270 mg/L

Sodium (Na)............................................. 3.75 to 4.50 mg/L

Chloride (Cl)............................................. 6.58 to 15.7 mg/L

Sulfate (SO4)........................................... 13.0 to 19.4 mg/L

Calcium (Ca)......................................................... 170 mg/L

Magnesium (Mg)........................................ 110 to 120 mg/L



Other Water Chemistry Levels

General

Dissolved Oxygen................................. 9.12 to 12.0 mg/L

pH............................................................ 7.7 to 7.8 units

Hardness................................................ 290 to 300 mg/L

Redox Potential......................................... 529 to 659 mV

Temperature........................................ 10.7 to 14.8 deg C

Inorganic, Non-metals

Alkalinity, Total.................................................. 270 mg/L

Bromide................................................ 0.02 to 0.09 mg/L

Nitrogen, Ammonia, Total.................................. 0.02 mg/L

Nitrogen, Nitrate plus Nitrite, Total..... .Less than 0.05 mg/L

Nitrogen, Nitrite, Total....................... .Less than 0.01 mg/L

Phosphate, Total.................................. .0.03 to 0.05 mg/L

Inorganic, Metals

Arsenic............................................. Less than 0.01 mg/L

Barium.................................................. 0.08 to 0.24 mg/L

Iron....................................................... 0.04 to 0.60 mg/L

Manganese........................................... 0.01 to 0.35 mg/L

Potassium............................................ 1.62 to 6.84 mg/L

Strontium.............................................. 0.09 to 0.52 mg/L

Organic

Organic Carbon, Total............................ Less than 1 mg/L

Please help me make sense of it. Thanks in advance!

 

[mabrungard]

Those Ca and Mg values are reported "as CaCO3". The resulting ion concentrations seem to fall to about the following levels (ppm).

Ca 68
Mg 28
Na 4
SO4 16
Cl 11
HCO3 329

Don't think of ever adding any magnesium salts to that water, the Mg is already high enough. The water is plenty hard and very alkaline. It can be brewed with, but may not make the best beers. The Fe and Mn are generally OK, but it appears that there are excursions in their levels and that could create metallic flavors in beer (and water). The water is reasonably suited to lime softening and that will help reduce the Ca, Mg, and HCO3 levels. Preboiling the water is another option for reducing Ca and HCO3 levels. A better bet may be to employ RO treatment for all or a portion of the brewing water.

 

[KeninMN]

Thank you for the reply, Martin! Prior to receiving the report I knew the water was super hard; it was everything else I wasn't sure of, so in the meantime I've been using distilled water and building it up from there.

 

[ajdelange]

It's not clear what they are reporting with respect to alkalinity. I think it must be the component of alkalinity attributable to carbonate and the amount attributable to bicarbonate. And I think the units must be ppm as CaCO3. But if that is the case they are not doing it quite right. That is not the correct ratio for pH 7.6 but it is close (if bicarbonate attributable alkalinity is 270 then that attributable to carbonate is, 0.92 (@ 20 °C). Ask them if they measured M or T (the same thing) alkalinity and what that number is. That's what you need to know. It will doubtless be very close to the bicarbonate number they gave you.

 

[KeninMN]

Thanks AJ! I can ask, but I may not get an answer for a very long time. As it was it took me two months to get this information...

So if I'm reading this correctly, my tap water is acceptable for nothing as-is, and only for the darkest, maltiest styles with nothing less than 50% dilution with distilled or RO water. Is that correct?

 

[Hermit]

Thanks AJ! I can ask, but I may not get an answer for a very long time. As it was it took me two months to get this information...

So if I'm reading this correctly, my tap water is acceptable for nothing as-is, and only for the darkest, maltiest styles with nothing less than 50% dilution with distilled or RO water. Is that correct?

I always suggest that once you have a water report that you plug the numbers into one of the many free applications and play around with it. I use Brewer's Friend for convenience but take your pick. I know it lets you blend waters to match profiles.

 

[ajdelange]

Thanks AJ! I can ask, but I may not get an answer for a very long time. As it was it took me two months to get this information...

We are talking fine distinctions here. Often times the utilities really don't know exactly what they are doing. They may be following 'the manual' which was written back in the 30's.

So if I'm reading this correctly, my tap water is acceptable for nothing as-is, and only for the darkest, maltiest styles with nothing less than 50% dilution with distilled or RO water. Is that correct?

It has a lot of temporary hardness and not too much else in which sense it resembles Munich water. There is a good possibility that it could be appreciably decarbonated/softened by heating or lime treatment. You would have to do that to be successful with most beers or you would have to deal with the alkalinity by neutralizing it with acid which replaces bicarbonate ion with the anion of the acid you use. This can be a viable technique if you wish to increase sulfate at the same time you want to decrease alkalinity. You would add sufuric acid (FCC please).