In truth, restrooms were rare throughout the Victorian era. It wasn't until the late 1800s that older residences were converted to incorporate bathrooms. Only in the early 1900s were all but the smallest houses built with an upstairs bathroom and toilet.
The most common form of sanitation during this time was the public bath. These were often found in large cities where water was scarce. People would go to the baths, where they could use the facilities, wash themselves, and get a good scrubbing at the same time. The public bath could be anything from a simple wooden structure with no more than two or three rooms, to a lavish complex with hundreds of seats, a theater, and even a golf course!
The public bath was so popular that many towns erected their own versions of the public bath as a way to save money. This is why you will sometimes see photographs or paintings with scenes that look quite familiar, such as a town square with buildings surrounding a large fountain. In reality, these places were usually the local town halls with bathrooms. They were used for meetings, parties, and other events which required a lot of people coming together at one time.
Inside the public bath, people would use towels to wipe themselves down before and after using the facility.
Anything else would have been too expensive. According to most historians, there were two sorts of Victorian bathrooms: wood-filled chambers and later sanitary porcelain white baths. I believe there is a third option, which I'll refer to as the hybrid. The first Victorian baths were simply installed in normal rooms. They were wooden boxes with a hole in the front for the water to enter. There was usually a faucet on the wall above the bathtub for washing hands or shaving. These were common in houses built before 1816, when indoor plumbing became generally available. In more affluent homes, this simple bath might be enclosed by a glass door or panel that could be opened for cleaning.
As time went on, people began to complain about the smell from these wooden baths. So Charles Dickens, in his novel "The Pickwick Papers", described a "modern bathroom" as having "a floor and a ceiling, and walls enough to contain it". In other words, a wooden box with a roof! In fact, many Victorian baths didn't have any walls at all. They were just big enough to fit a tub inside of them.
In 1856, an English company called Lucas produced one of the first practical plastic materials, called Melton Mowbray stone, after the town where it was invented. This new material was used for bathtubs because it was hardwearing and easy to clean.
Houses were not built with bathroom facilities until the late Victorian era. If there was a toilet room, it would be more convenient and less stinky to locate it in the garden, where waste disposal (typically by council-run dung carts) would be easier to handle. The house needs to be at least 50 years old for it to be considered an "old house."
The term "outhouse" is still used today to describe a structure for providing relief to people who live in remote areas without nearby bathrooms. The original outhouses were simply holes in the ground with a cover over them. Today's outhouses can be as simple or sophisticated as you want to make them. Some even have lights and heaters attached to keep your toes warm in the winter and your hands cool in the summer.
Not all old houses have these outdoor toilets. Many early American homes had indoor plumbing with no separate room for storing urine or feces. Instead, they disposed of their waste by burying it in backyard pits called "night soils." These practices ended up giving rise to words like "indoor" and "outdoor" furniture.
So, toilets weren't easy to come by back then, and if you wanted one you'd better like the idea of doing your business outdoors!