Z.A.
I feel ya...my son was over 10lbs and 23 inches long when he was born. We used a big round toy bin/bucket, the kind with rope handles that you can get at target/fred meyer etc.
Actually, my son loved the water so much that once he could sit up, he used to splash around in there, while I drug it from room to room cleaning. I just added warm water as necessary.
Boy did I feel trapped once he got too big for THAT. I have to stay in one room??? Really???????? Argh.