The time required to install an outdoor shower can depend on several factors such as the complexity of the design, the availability of utilities (like water supply and drainage), the type of materials used, and the expertise of the installer. In general, a straightforward outdoor shower installation may take anywhere from one to three days to complete. However, more intricate designs or those requiring extensive plumbing or construction work could take longer, potentially up to a week or more. It's best to consult with a professional installer for a more accurate estimate based on your specific requirements and conditions.