They are gently lighted and spacious and lined with pristine tiles. They are as cramped as Port-O-Lets, splashed with graffiti and redolent with urine. They can be found behind sliding barnlike doors, down rickety staircases, through fry cooks’ kitchens or, just as often, not at all.

They are the bathrooms of New York, a vexingly elusive quarry that, under recent changes to a city code, could become harder still to find.

Under legislation that Mayor Michael R. Bloomberg signed on Aug. 8, small restaurants and coffee shops with an occupancy of 30 people or fewer are allowed to provide patrons with one bathroom rather than two, as previously required — one for each sex. The changes also brought the city’s plumbing code in line with a health department code that allowed places with fewer than 20 seats to not provide patrons with any bathroom.

In short, in a city already starved of places to answer nature’s call, the future may hold fewer options.