No Mg on my tap water? Is that even possible?

[p_p]

My water company publishes a fairly comprehensive yearly report.
The report includes averages for all the basic ions we are intereted in, except they don't list Mg.
Now, the strange thing is that the Ca hardness matches the total hardness in the report ...

I usually do a KH&GH test prior brewing and use the data to adjust my estimations of Ca, Mg and Alkalinity, leaving the rest of the ions as declared in the report. The GH values from my test always match +/- 20ppm that in the report.

Is it possible that my water has no Mg? (I haven't splashed on a Ca Mg Salifert test, I must admit).
I understand in most waters the hardness contribution is 70-30% split between Ca and Mg .. but 100-0%? mmmmm

I am in the London area. The declared values for 2014 are Ca 117 ppm, Total Hardness 293 ppm as CaCO3.

thanks

 

[BobBailey]

Very possible that your water has less than 1PPM Magnesium. My ware report lists Magnesium as less than 1PPM . Very possibly your water supplier just doesn't list mineral concentrations lower than 1PPM.