Table 1. Main mineral element contents and pH values of the four types water.

	TW	bNW	bMW	bPW
pH value	7.57	7.55	6.80	6.80
Total dissolved solids (mg/L)	229	87.2	10.9	1.2
Total hardness(CaCO3, mg/L)	200.3	69.6	2.3	0.8
Calcium (mg/L)	52.9	10.6	0.02	0.04
Magnesium (mg/L)	12.7	9.4	0.4	0.02
Sodium (mg/L)	12.4	9.0	0.1	0.1
Potassium (mg/L)	2.5	3.8	3.4	≤0.5