| Value | Category | Cases | |
|---|---|---|---|
| 1 | boiling | 18 |
1.1%
|
| 2 | chlorination | 208 |
13.3%
|
| 3 | chlorination filter | 2 |
0.1%
|
| 4 | filter | 369 |
23.5%
|
| 5 | filter safe | 2 |
0.1%
|
| 6 | none | 130 |
8.3%
|
| 7 | other | 11 |
0.7%
|
| 8 | safe | 539 |
34.4%
|
| Missing value | 290 |
18.5%
|