Well the post above mentions that distilled and RO water need calmag+,
and I thought that was because that water is pure with no TDS in it.

And I thought tap water with higher ppm already has calcium and magnesium?
bobhead Reviewed by bobhead on . Does Low PPM Water Need Calmag+ ? I just got my TDS PPM Meter. I tested my tap water and it has around 35 PPM. Does this mean I need calmag+ ? Rating: 5