Not that the water flowing from the water is clean or dirty. It is not possible to filter the water that is clean enough to be filtered comes or not has been a water filter change filter every 2 months.
The water that flows from upstream to clean or dirty. Filter was unable to make the water clean enough to be filtered out. Water or not to change the filter every two months.
Whether the water flows from headwaters to clean or dirty. The filter will not be able to make the water clean filtered to do it. Or the filter has not been transformed 2 filter every month.