Thanks to Virginia for pointing this one out! I haven't been able to find any reviews, though.
Barry Hobson, Latrinae Et Foricae: Toilets in the Roman World (Duckworth, 2009)
The Romans are renowned for their aqueducts, baths and water systems, achievements equalled in the modern world only over the past few hundred years. Their toilets, both single ('latrinae') and multi-seater ('foricae') form part of the Roman sanitation system that continues to fascinate the modern visitor to ancient sites today. In this well illustrated overview, Barry Hobson describes toilets in the Roman empire from Iberia to Syria, and from North Africa to to Hadrian's Wall. Particular emphasis is given to Pompeii, where many toilets are preserved and where some evidence for change over time can be found. The discussion encompasses not only details of location, construction and decoration of toilets, but also questions of privacy, sewage, rubbish disposal, health issues, references in Latin literature, and graffiti.
Barry Hobson was a GP until he retired in 1997 following which he undertook a degree in Archaeology at the University of Bradford and then a Research Masters degree. He has spent twelve seasons working at Pompeii and has travelled extensively looking for evidence of Roman toilets.