Holy crap! I have been using 170ppm TDS water!

[Aquattro]

What people need to understand is that TDS doesn't equal bad. It's just a measure of total dissolved solids. Of course those DS's could be bad, we have no (easy) way to tell. Calgary for example, has very high TDS. But much of that is mineral content from the water source. Not a bad thing at all. Areas near agricultural areas might be a bit more concerned, as run off also measures as TDS, which can be N or P compounds, and/or toxic compounds. Again, risk is low, but cost of RO to offset that risk seems negligible, at least for medium to larger tanks.