Mike, I knew Bill well, years ago we lived several blocks from each other in Plainfield, N.J. I can vouch that the book is probably the finest work on water towers ever compiled. Unfortunately I lost my copy in the move to Virginia, but I'll check some of the local vendors to see if they have any available.
I actually do have a couple of water tower books still available. They typically go for $300 on ebay and amazon, I will sell one for $200. Email email@example.com or best way is call my cell phone 916-271-3221