After removing your air filter gently tap to remove any loose debris.
Fill a 5-gal or similarly sized bucket with warm soapy water; a mild dish soap works best.
Submerge your filter into the water with the narrow end pointing down, and the large flange pointing up (like an inverted Christmas tree). This will help the dirt fall down to the bottom of the bucket.
Let it soak for 20-30 minutes before pulling out to rinse. Rinse using gentle, low pressure from the inside out to prevent pushing any dirt deeper into the filter. Rinse until the water runs clean.
Gently shake out excess water and then hang your filter to dry naturally; at least overnight but preferably 24 hours.
You want to ensure the filter to be completely dry when you reinstall it; if it’s wet when you put it back in it can cause some restriction in air flow, causing a pressure differential across the filter that may cause it to wrinkle or ‘suck in’ like a vacuum.
You don’t want to use compressed air to speed up the process as the direct force can damage the filter media.
Tip: Many customers who use washable filters choose to keep an extra on hand, so they don’t have to have their truck down during the washing and drying time.