The way purifiers work, the treated water is generally very light (reverse osmosis), i.e. it has a low content of mineral salts and solids in general. This characteristic of purified water can be confirmed at any time and instantly by checking two parameters, the fixed residue with the TDS instrument and the electrical conductivity with the conductivity meter.
A value between 20 and 130 microsiemens/cm of electrical conductivity is a guarantee of high quality water with an excellent purifying effect.