The Sterasyl filter should be cleaned and very 4 to 6 week but this will depend on the Quality of water used in the first place. The filter is a final stage filter the cleaner the water to start the long between clean.
The "drip rate" should be one litre per hour when it slows down it is time to clean.
Remove well from pot.
Undo wingnut and remove filter Sterasyl.
Gently scrub the Sterasyl with a 3 mm scuch removing the scum and rinsing the filter. Clean the well under running water. Do not use soap, chemicals are what we are wanting avoid after all! If you want, wash the well and the Pot with vinegar and rinse off with water.
Replace the Sterasyl in the well. Don’t over tighten the wingnut, just finger tight and gently place back in the pot and fill with water.
If installing for the first time or replacing the filter please read the instructions on the box. It is best to soak the Sterasyl upside down in a pot of water for 12 hours before installing.