You should wash the pre-motor filters occasionally to keep your vacuum working great. We recommend washing these every month. You can also tap loose dirt off filters between washes as needed. To wash, simply remove the dust cup, remove the foam and felt filters underneath, wash both under tap water until the water runs clean, squeeze out excess water and let air dry completely for at least 24 hours. Once dry, replace the filters back into your vacuum, starting first with the felt filter, and then adding the foam filter on top. It is important to note that your foam filters may appear dirty after first use " this is normal. These filters will discolor over time " this is also normal.