Nigel Calders Book has a small section
It sounds as if you are looking for a book on just marine plumbing, but Nigel Calders book (listed below) does have a chapter on "Plumbing, Tiolets & Thru hull fittings". Not exactly an all encompassing peice, but it does have diagrams and will get you started and on the basics. From there you can refer to "the Head Mistress's" section here for some more detail and suggestions, etc. The other good thing about this book is that is has practically ALL systems that you would encounter on a sailboat (mechanical, engines, rigging, etc). And is looked at as a "Bible" for Boat maintenance, etc.(Most online book store like Amazon or boat related sites have it) Its called...."Boatowner's Mechanical & Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems"by Nigel Calder