| · Not to open the sample bottle except in front of the tap and sterilize its nozzle with flame | - | - | 30 (100%) |
| · Wrap the cap with a gauze | - | - | 30 (100%) |
| · Putting the bottle in a special coalman surrounded by snow | - | - | 30 (100%) |
| · The result of the processed sample corresponds to decree of 63 for 1996 during the last month | 4 (13.3%) | - | 26 (86.7%) |