1, the chromaticity does not exceed 5 degrees to ensure that the water is clear and transparent.
2, turbidity does not exceed 0.5 NTU, that is, 500nm turbidity unit, to ensure that there is no suspended particulate matter or microorganisms in the water.
3, pH value between 6.5 and 8.5 to ensure that the water has the right acidity and alkalinity.
4, total dissolved solids (TDS) of no more than 10mg / L to reduce the amount of dissolved matter in the water, including soluble salts, heavy metal ions and so on.
5, the total number of bacteria does not exceed 100CFU/mL, in order to avoid microbial contamination on human health adverse effects.