Table 3.
Quality of water from samples collected from taps and storage containers when water treatment systems were fully operational and during treatment interruptions.
| WTS Fully Operational | Treatment Interruption * | |||
|---|---|---|---|---|
| TAPS n (%) | Containers n (%) | Taps n (%) | Containers n (%) | |
| Number of samples | 369 | 77 | 83 | 13 |
| E. coli (MPN **/100 mL) | ||||
| <1 | 363 (98.4) | 69 (89.6) | 81 (97.6) | 12 (92.3) |
| 1–10 | 6 (1.6) | 5 (6.5) | 1 (1.2) | 0 (0) |
| >10 | 0 (0.0) | 3 (3.9) | 1 (1.2) | 1 (7.69) |
| Total Coliforms (MPN **/100 mL) | ||||
| <1 | 344 (93.5) † | 53 (68.8) | 70 (84.3) † | 9 (69.2) |
| 1–10 | 16 (4.4) | 10 (13.0) | 6 (7.23) | 1 (7.69) |
| >10 | 8 (2.1) | 14 (18.2) | 7 (8.43) | 3 (23.8) |
| Number of samples | 364 | 76 | 83 | 13 |
| Free chlorine residual (mg/L) †† | ||||
| Mean | 0.13 | 0.11 | 0.02 | <0.02 |
| Median | 0.02 | 0.02 | <0.02 | <0.02 |
| Range | <0.02–2.20 | <0.02–2.20 | <0.02–0.17 | <0.02–0.04 |
| Total chlorine residual (mg/L) †† | ||||
| Mean | 0.19 | 0.15 | 0.06 | 0.02 |
| Median | 0.07 | 0.04 | 0.04 | 0.02 |
| Range | <0.02–2.20 | <0.02–2.20 | <0.02–0.26 | <0.02–0.09 |
| Turbidity (NTU) | ||||
| Mean | 1.09 | 1.30 | 1.17 | 1.49 |
| Median | 0.71 | 0.62 | 0.74 | 0.74 |
| Range | 0.02–20.07 | 0.12–26.6 | 0.05–6.92 | 0.12–5.76 |
* Treatment interruption indicates periods when the mechanisms for ensuring safe water at the point of use, such the chlorine dosing mechanism, were compromised. ** Most Probable Number. † During treatment interruptions, samples collected from taps were 2.66 times more likely to have one or more total coliforms MPN per 100 mL (OR: 2.7, 95% CI: 1.3–5.5) compared to tap samples collected when the MF systems were fully operational. †† Limits of detection for free and total chlorine residual were 0.02 to 2.20 mg/L.