For research on private toilets in Roman houses, see Jansen, “Water Systems and Sanitation in the Houses of Herculaneum,” Mitteilungen des Leichtweiss-Instituts für Wasserbau der Technischen Universität Braunschweig 117 (1992), pp. 449–468; “Private Toilets at Pompeii: Appearance and Operation,” in Sequence and Space in Pompeii, eds. Sara E. Bon and Rick Jones, Oxbow Monographs 77 (Oxford: 1997), pp. 121–134; and “Systems for the Disposal of Waste and Excreta in Roman Cities. The Situation at Pompeii, Herculaneum and Ostia” in SORDIS URBIS: L’eliminazione dei rifiuti nella città romana, ed. Xavier Duprè Raventós (Rome: 1999).