The bathroom drain is blocked.
in-ta-SA-to — four syllables, stress on the third.
Report a blocked drain or toilet immediately. Do not attempt to fix it yourself — contact reception.
'Intasato' (blocked/clogged) comes from 'intasare', which means to block or clog. It applies to drains, toilets, and sinks. 'Il bagno' can refer to the bathroom as a whole or the toilet specifically — context clarifies.
Il WC è intasato.
The toilet is blocked.
More specific term for a blocked toilet — 'WC' is universally used in Italy
Lo scarico della doccia non va.
The shower drain is not draining.
Report a slow-draining shower before it becomes fully blocked
Il lavandino è ostruito.
The sink is blocked.
'Ostruito' is slightly more formal than 'intasato'
Italian plumbing in historic buildings can be temperamental. Never flush anything other than toilet paper — facial wipes, cotton pads, and other items cause instant blockages. Some Italian bathroom signs politely request this ('Non gettare nulla nel WC tranne carta igienica').