Water question - RO water and alkalinity

[rkhanso]

I think I know the answer, but thought I should ask anyway.
My city has bad water for brewing. Very high alkalinity. I have to use RO water from the local grocery store.
But as I was filling the 5gal jugs today, I saw a sign there saying I'm getting RO water using the same city water at my home, which has very high alkalinity.
Is the RO filter correcting the high alkalinity for me? Am I good using this RO water? Or is it also questionable since the source is from the same city supply?
My inclination is that the water is OK.
Thanks.

 

[Silver_Is_Money]

The RO unit is likely removing at least 90% of the alkalinity. And about 95% of everything else. Depending upon the recipe, you may still need to remediate some remaining alkalinity (and more) via acidification, or alternately, for a dark brew you may need to add back additional alkalinity, and you will always need to add back some (recipe dependent) level of minerals.

 

[mabrungard]

Carbonate and bicarbonate ions are rejected well with the RO process. You will have a substantial reduction in their concentrations. At least 95% reduction, but that assumes that the machine is operating well. All RO users should have a TDS meter so that they can confirm that the water has very low TDS.

 

[Yooper]

I bought a very cheap aquarium test kit that tests gH and kH. I use it to tell me how my RO filter is working at my house. I have an alkalinity of something like 228 ppm, and the aquarium kit tells me my carbonate hardness and general hardness both are under 17 ppm. That's one way to ensure the alkalinity is low, but not precise as to the amount.

 

[rkhanso]

Thanks for that info. I feel better about it now. Beer brewed and in the fermenter.

BTW, the Ward Labs water report:
Total Alkalinity (CaCO3) is 391.
Bicarbonate (HCO3) is 476.
Total Hardness (CaCO3) is 510
Total Dissolved Solids is 565

Thus - I use RO water.

 

[day_trippr]

Yeah you do

 

[balrog]

I'm surprised it even flows...

 

[Silver_Is_Money]

Thanks for that info. I feel better about it now. Beer brewed and in the fermenter.

BTW, the Ward Labs water report:
Total Alkalinity (CaCO3) is 391.
Bicarbonate (HCO3) is 476.
Total Hardness (CaCO3) is 510
Total Dissolved Solids is 565

Thus - I use RO water.

My well water:
Total Alkalinity (CaCO3) is 437
Bicarbonate (HCO3) is 533
Total Hardness (CaCO3) is 758
Total Dissolved Solids is 876

 

[ScrewyBrewer]

Yikes!