Those new discus are awesome! And 138ppm out of the tap isn't bad at all. In fact, that water is perfectly fine for domestics. You need to get it lower when you try to start breeding them. And with wilds, well those guys just come from very soft water of 10-30ppm.
I've read about people that have 500-600ppm out of the tap, now that water is bad! Had an interesting situation with my tapwater. It jumped from 110ish to about 340ppm for a few days! Not sure what caused it. And now it's back to 90-100ppm. Those couple days with high TDS levels really made a difference on my sediment filter. Since it's fairly new, the filter was still white. But in just a few days it was brown with all the increased particles!