The owner's manual for a Shark Rotator powered lift-away vacuum prescribes cleaning the foam filter and felt filter every three months, and it advises owners to clean the HEPA filter every 12 months. The product page for the Shark Navigator lift-away vacuum encourages customers to purchase replacement filters to install while regular filters dry after cleaning.
The instruction manual states owners should tap each filter after use and between washings to lessen the amount of dirt and dust that accumulates on the filters. Remove the dust cup and rinse the foam and felt filters with running water every three months. After rinsing, allow the filters to air dry completely before reinstalling them and continuing use.
At this point, you may need to install replacement filters if you need to continue vacuuming. Remove the back grill of the vacuum to find the HEPA filter, and then rinse this filter with running water once every 12 months. As with the other two filters, allow the HEPA filter to air dry completely before placing it back into the machine.
Order a replacement set of filters through the company's website or by calling customer service. National chain retailers may also carry Shark vacuum replacement filters.