| Biofilter | Units | Sand 1 - 2 mm | Sand 2 - 4 mm | Lateritic gravel 2 - 4 mm | Lateritic gravel 4 - 6 mm | Granitic gravel 1 - 2 mm | Granitic gravel 2 - 4 mm | Granitic gravel 4 - 6 mm | |
| pH | - | 7.21 (0.38) | 7.29 (0.52) | 7.19 (0.31) | 7.26 (0.37) | 7.16 (0.32) | 6.99 (0.36) | 7.25 (0.34) | |
| COD | mg/L | 577.5 (204.85) | 1015.86 (474.14) | 1248.25 (317.42) | 1325.58 (241.11) | 777.5 (319.03) | 1144.25 (326.86) | 1335.5 (257.84) | |
| BOD5 | mg/L | 215 (109.20) | 360 (173.29) | 593.75 (152.47) | 695 (263.04) | 267.5 (68.63) | 475 (136.17) | 551.67 (302.32) | |
| SS | mg/L | 170.14 (152.83) | 143.90 (95.10) | 357.42 (158.22) | 532.56 (210.38) | 245.5 (221.41) | 342.92 (188.01) | 654.41 (250.60) | |
| E. coli | CFU/mL | 8.91 × 104 (1.08 × 103) | 1.47 × 106 (1.43 × 106) | 3.02 × 105 (7.96 × 104) | 7.76 × 105 (5.63 × 104) | 4.36 × 104 (2.65 × 102) | 4.17 × 105 (1.62 × 104) | 7.24 × 105 (5.20 × 104) | |
| FC | CFU/mL | 4.67 × 106 (1.45 × 106) | 2.88 × 107 (2.85 × 107) | 5.37 × 107 (3.00 × 107) | 4.26 × 108 (5.72 × 107) | 6.91 × 107 (4.03 × 107) | 2.57 × 107 (2.21 × 107) | 9.12 × 107 (5.72 × 106) | |
| Enterococcus | CFU/mL | 3.98 × 104 (4.86 × 103) | 4.26 × 104 (8.12 × 103) | 2.57 × 105 (7.57 × 104) | 8.12 × 106 (7.59 × 106) | 9.12 × 104 (3.90 × 103) | 2.09 × 105 (4.49 × 104) | 2.34 × 106 (1.21 × 106) | |