The ISO standard 3696 defines 3 different grades of water:
Parameter | Grade 1 | Grade 2 | Grade 3 |
Conductivity μS/cm (Temp Corrected) | <0..1 | <1.0 | <5.0 |
pH at 25 ̊C | N/A | N/A | 5.0-7.0 |
Oxidizable matter Oxygen (O2) content mg/L | N/A | <0.08 | <0.4 |
Absorbance at 254 nm and 1 cm optical path length, absorbance units | <0.001 | <0.01 | N/A |
Residue after evaporation on heating at 110 ̊C mg/kg | N/A | <1 | <2 |
Silica (SiO2) mg/L | <0.01 | <0.02 | N/A |
DiaSys water purifiers are able to produce water of Grade 2.