Help with my brewing water

I've recently taken the leap into all grain and began educating myself on brewing water. My water report from the city shows I am going to have major problems using water straight from the garden hose. The readings in mg/L

208 Calcium
149 Magnesium
42.1 Sodium
297 Alkalinity
80.5 Chloride
46.2 Sulfate

I see my magnesium level is ridiculously high. My question is if I could possibly lower my calcium and magnesium by using water that has been through my softener? Can anybody give me a rough approximation of what a softener will do with those values? I understand it adds sodium, but too much to put it out of range? Any suggestions on other ways I can solve this or is this water hopeless? I'm trying to avoid the added cost and hassle of buying large quantities of distilled water.

Yes, your magnesium is out of sight. Where do you live? What's the source of the water?

A softener will remove most of the calcium and magnesium. Normally softeners take these down to 1 - 2 mg/L. With your incoming levels so high you might see a bit more.

Your calcium is 208/20 = 10.4 mVal and the magnesium 149/12.15 = 12.3 mVal for a total hardness of 22.7. These will be replaced by sodium. With its equivalent weight of 23 that comes to 521 mg/L sodium. That's a lot of sodium but you really don't have many options for brewing with this water.

You could try removing the magnesium by the use of the 'split' lime treatment. You can probably expect to get rid of a bit more than half of it that way. The other half of the 'split' will get rid of a lot of the calcium too. A more practical approach might be to soften the water first and then use an RO unit to remove the sodium and most everything else. The softening is necessary to prevent calcium carbonate from precipitating on the RO systems membrane. Once the gear is installed and paid for this is simpler than the lime treatment. But even with RO you will have to watch the system like a hawk. At 98% rejection your sodium would be at 10 mg/L, at 96% 20. Fortunately this monitoring is easy to do with an inexpensive TDS meter.

Thanks for your suggestions. I live in Maple Grove, Minnesota. The city draws well water from two different underground aquifers.

Ajdelange, what are the calculations you're doing to get total hardness? My water report does not list total hardness, alkalinity, or bicarbonates. Is there a way to determine these numbers, or do I need to get my water analyzed? Here is a link to the report, if you wouldn't mind taking a look. https://www.calwater.com/ccr/2012/chico-ch-2012.pdf

Thanks !

As hinted at in #2 the calcium hardness is the mg/L calcium divided by the equivalent weight of calcium, 20, and then multiplied by 50 which is the ppm as CaCO3 per mEq. For magnesium the equivalent weight is 12.15. If you apply these numbers to the average calcium and magnesium numbers in your report you and add them together you should get close to their total hardness number.

There is nothing in your report to give a hint about alkalinity (or bicarbonate). You could WAG at it by assuming that everything is reported except bicarbonate/carbonate and calculating the amount of carbo (carbonic + bicarbonate + carbonate) required at the given pH to bring about a net charge of 0 given the charges on the other ions. This is a little iffy.

Thanks a lot! I'm going to dig a bit to see if I can find the bicarbonates and/or alkalinity from the company. When looking at my numbers, they're very close (just slightly higher) to your categorization of soft water on your sticky about water, but with a total hardness of 126, the water company is classifying that as moderately hard. I'm a little confused.

Kalmah said:

Thanks for your suggestions. I live in Maple Grove, Minnesota. The city draws well water from two different underground aquifers.

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I live a couple 'burbs away from you and our water has about the same hardness. Also, lots of iron. I have a water softener, but it doesn't filter iron, and besides, the resulting Na would be sky high. I buy RO water in bulk at Cub Foods for $0.39/gallon and add my own salts. Cheaper for me than buying filtration equipment.