The KN filter can be washed BUT not under pressure from a water hose it will destroy it. They sell the kits with soap and oil in it. The filter is a wet filter. Washing it take some mild dish soap and water in a bucket and just gently move it around in the bucket then do it again with clean water. Do not use pressurized aid to dry it. Drop dry only. Then you find the filter oil and coat the filter and let it set so the excess oil can drop off.