Langelier Saturation Index

SI = PH + TF + CF + AF - TDSF

Temp.

TF

Calcium Hardness
(mg/L)

CF

Alkalinity
(mg/L)

AF

0.0
2.8
7.8
11.7
15.6
18.9
24.4
28.9
34.4
40.6

0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

25
50
75
100
125
150
200
250
300
400
800

1.0
1.3
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.5

25
50
75
100
125
150
200
250
300
400
800

1.4
1.7
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.9

TDS under 800 mg/L = 12.1
TDS between 801 and 1,500 = 12.2
TDS between 1,501 and 2,900 = 12.3
TDS between 2,901 and 5,500 = 12.4
TDS over 5,500 = 12.5

Saturation Index between -0.3 to 0.5 is Balanced Water (ideal)
0.1 and Over = Scale Forming
-0.1 and Lower = Corrosive