At our county dump, there is a shed with a tank for used oil. The entire top of the tank is a drain pan, (tank probably holds 300 gallons). At one end of this pan is a rack where you can leave your filters. The idea is that you place them there so they drain into the pan and thus into the tank. What they do with them after that, I have no idea. I throw mine into a five gallon bucket and leave them there till I'm ready to take a trip to the dump and place them on the rack. I don't know what the max filter allowance is, but one time I had like 12-15 filters and the guy got onto me. But I told him these were from many oil changes over time, (I think he thought I was bringing them from a shop). He finally let me put them all there but warned me "not to do it like this again."