Value of FBI | Water quality | Degree of organic pollution |
0.00 à 3.75 | Excellent | Without organic pollution |
3.76 à 4.25 | Very good | Slight organic pollution |
4.26 à 5.00 | Good | Probable organic pollution |
5.01 à 5.75 | Average | Substantially organic pollution |
5.76 à 6.50 | Rather bad | Substantial organic pollution |
6.51 à 7.25 | Bad | Very substantial organic pollution |
7.26 à 10.00 | Very bad | Serious organic pollution |