Complete Dirty Tank Assembly for Select BISSELL Portable Carpet Cleaners. To Empty the Dirty Tank, follow these instructions: Empty dirt water tank when it reaches "MAX" line. Do not let water level fill above the MAX line. Remove dirty water tank by tilting outward and carry to a disposal area. Pull up on dirty tank lid to remove. Pour out dirty water and rinse tank. Reinstall tank lid. Insert bottom of tank first and push top of tank toward machine until it clicks into place. Dirty Tank Assembly 1638664