| Sub-catchment | Village | Population | No. Household | Sample size |
| Lower Mngeta | Mngeta | 5811 | 999 | 100 |
| Mofu | 2364 | 1021 | 102 | |
| Mchombe | 5421 | 1339 | 134 | |
| Total | 13596 | 3359 | 336 | |
| Upper Zigi | Sakale | 1138 | 400 | 40 |
| Kisiwani | 1269 | 316 | 32 | |
| Bombani | 1021 | 448 | 45 | |
| Nkumba | 996 | 246 | 25 | |
| Total | 4424 | 1410 | 142 |