No, it is not recommended to wash the Coarse Particle Pre-Filters. Depending on the project, one filter should last one job (or up to 30 days). The pre-filters can be shaken out when dirty, and you can do this multiple times over the course of a project, but they should not be washed. You want to always use a clean pre-filter to keep the HEPA 360 Air Scrubber performing optimally and to ensure the life of the HEPA Filter. To avoid liability issues, a new pre-filter should be used at the start of every job.