HOMEBASED FULL-FLEDGED "PROCESSORS" ALLOWED IN WASHINGTON
SECONDARY RESIDENTIAL KITCHENS FOR FOOD PROCESSING
"HOME PROCESSOR" LICENSES ARE ISSUED BY WSDA aka WASHINGTON'S state-level DEPARTMENT OF AGRICULTURE. Their food processor application is shown in the image to thee right. It is snipped from the top of Application's page 2. As you see, secondary-kitchens can be created inside family homes, if commercial food processing is not disallowed by local zoning, etc... and water and waste disposal serving the secondary-kitchen is up to local county standards (which vary from county to county)
You can view the entire WSDA Food Processor Application @ https://cms.agr.wa.gov/WSDAKentico/Documents/Forms/2090-Food-Processing-New-License-Application-Rev-4-2019.pdf?/2090-Food-Processing-New-License-Application-Rev-4-2019&_gl=1*f7q8qr*_ga*MTQ3MTYwNjMyNS4xNzQ1NDkzNjM5*_ga_9JCK8SVQPE*czE3Njg0NDMxMjkkbzQ1JGcxJHQxNzY4NDQ0NDI4JGo1NyRsMCRoMA..
>>>> Further info; "Processing Equipment, Food Process & Equipment Cleaning Sinks
A Food Safety Compliance Specialist (FSCS) will review your specific equipment at the time of inspection. In general, equipment should be made from materials that are easily cleaned and in good repair. Stoves, refrigerators, dishwashers, and other appliances and motorized processing equipment NEED NOT be a "COMMERCIAL" TYPE as long as they are made from materials that are easily cleaned and the equipment is in good repair."
SEE EVEN MORE about home processing kitchen requirements AT https://agr.wa.gov/.../food-safety/food-processors/facility
click image to open WSDA Application form, see top of page 2