Our mu baan water supply is from a borehole, supposedly filtered, stored in one of those steel mushroom towers, and distributed through 30year old pipework. It arrives at our house full of rust and sediment, and is as hard as nails.
The monitor pen tests our incoming water at 600+ppm.
Water from Makro, 6litres various brands, measures anything from 30-60ppm out of the bottle.
Drinking Water from our RO filter is consistently 10ppm or less. The previous one, which went faulty and had to be replaced, used to give 12-13ppm.
Water from roadside coin-op RO dispensers, very variable, mostly you don't want to know and the green slime is a bit off-putting.
Our communal swimming pool runs at about 200ppm, but it's not a well kept system and frequently turns green. Our management is incapable of understanding basic pool chemistry!
The ppm monitor also measures water temperature, in this hot weather the incoming runs at 28C. One day it hit 32! That's hotter than the cool wash program in our washing machine!