| Value | Category | Cases | |
|---|---|---|---|
| 1 | porous cesspit | 108 | 
                                                                 
                                    
                                    39.9%
                                 
                                                             | 
                                                        
                    
| 2 | Sewage network | 40 | 
                                                                 
                                    
                                    14.8%
                                 
                                                             | 
                                                        
                    
| 3 | tight cesspit | 102 | 
                                                                 
                                    
                                    37.6%
                                 
                                                             | 
                                                        
                    
| 4 | Other | 21 | 
                                                                 
                                    
                                    7.7%
                                 
                                                             |