Quite easy mate, theres a tds meter hanging from it, run some water through into a glass, rinse it with the water a couple of times then fill up again. Test the water with the tds meter and if it's 000 it works if its too high it doesn't and someone will tell you what numbers to look for.
And do I presume right you're a breaking bad fan?
And do I presume right you're a breaking bad fan?