Sometimes if I remember, I put a disposable foil pan on the bottom grate under whatever I am cooking.. Makes clean up a breeze. If I forget I use a brillo pad to scrub, or dish soap and crumpled aluminum foil (works great) if I'm out of brillo.
Two pages of posts about foiling or cleaning the water pan. I guess Weber better get their engineers to focus on redesigning it. How about a stainless steel water pan? My ss rib racks clean up just fine in the dishwasher, but the black metal pan does not. They could also design a form fitting disposable foil pan that fits inside the water pan.