It really depends on the contents of the water more than the actual TDS levels; however, I would say the 250-300PPM area for tops. I have used it higher (400PPM) with no problems though, so...
gainesvillegreen Reviewed by gainesvillegreen on . ppm of tap water - whats tolerable? is there a cutoff level for ppm of tap water where it shouldnt be used? i use distilled and am wondering if i even have to. Rating: 5