While some bedrooms have private ensuite or dedicated bathrooms, most rooms will have a shared full bathroom between every 2 (absolute maximum 3) rooms.
That said, thanks to our roomie matching system, we'll be able to give you a good estimate of whether or not you'll be able to avoid fighting for the bathroom, no matter how many people you're sharing the bathroom with.
Note that many Roost also includes professional cleaning (see exactly listing for details)! In these cases, you'll be able to avoid the "who's turn it is to scrub the toilet and soap scum" discussion altogether.