Colonial bathrooms are characterized by a comfortable, minimalist style, as well as the use of several signature colors and textures. The American Colonial period, spanning roughly two centuries from 1600 to 1800, was a time of great historical significance, social and cultural transition, all of which is subtly reflected in the architecture and interior design of the era.
Color was an important element in the Colonial period. Paints were made from natural pigments, and so the available color range was fairly limited, encompassing cream colors for walls and woodwork, plus mustard yellows, light greens, soft blues and barn red. Another decorative aspect to consider for your Colonial bathroom is stenciling—because most colonists couldn't afford wallpaper, stenciling (often of flowers or other natural elements) was popular. You can reflect this historical design choice by adding stencils around mirrors or other fixtures.
Adding a few touches from a bygone era will give your Colonial bathroom a feeling of authenticity. One example is a chair rail—which, along with the wall below it, can be painted in bolder color than the rest of the bathroom walls, for a genuine Colonial look.
In terms of accessories, natural wood for towel racks, wrought iron for sconces, and wood frames for mirrors will reflect the utilitarian, simple beauty of the era.