With the advancement of modern science and technology, standards for the nature of water were raised, including:
1.  Suspended matter: content of insoluble solid substance isolated by filtration.
2.   Soluble solid matter: total content of soluble mineral elements.
3.  Hardness: content of the most common elements such as calcium and magnesium in                 natural water.
4.  Alkalinity: content of subjects which can accept hydrogen ions.
5.  pH value: a measure of the acidity or alkalinity of a solution
Water for brewing tea, should have a lower content of suspended matters, but no visible suspended particles. The water hardness should be less than 5 degrees, and pH less than 5. Surface water in non-saline areas can also be used