Some sediments, depending on the types and amount of contaminants in water, are very fine. Therefore, they may pass through the coffee filter. This is not uncommon since coffee filter are meant to trap relatively large coffee beans.
Suggestions:
1. Try using 2 - 3 coffee filters.
2. Filter using the Adya Clarity Gravity Filtration System.
It contains a 0.2 micron size Ceramic Filter that can trap the finest contaminants.
*Please note that the sediments are converted to a harmless form (which is inert) as the minerals neutralize the contaminants. If you consume the sediments, they will simply pass through your body.