Depends on the event and your local health dept. rules. AFAIK out here the teams are covered under a blanket permit pulled by the organizer. However if you want to compete in the peoples choice award you have to have the proper health dept. approved rig. Out here in my county that means fresh and Grey water tanks, triple sink for washing dishes, a separate stand alone sink for hand washing, and hot water (120+) as a starter. A "safe food handler" cert may also be required for any type of event you cook at. I am currently in design phase for a mobile rig that will meet health department regs in any county as I plan to use it for comps as well as private catering. After 3 years of research all I can say is slow down, take a step back and do some research. don't put the cart, or in this case the pit, before the horse. I know you are excited to move forward but if you jump the gun you will be severely disappointed.Look for an old, cheap travel trailer, that should give you your tanks, pump, and water heater. Use only NFS approved piping and materials. It may get expensive to do it right the first time, but it is cheaper than doing it twice, and better than getting discouraged when you get an "unapproved" stamp and say the heck with it. also, keep detailed pictures, drawings (blueprints), and receipts. I know out here I have to actually pull a build permit just like building a brick and mortar restaurant to get my rig legal as we build it.