No, rainwater can be used for both outdoor taps as well as indoor taps, subject to local regulations and treatment. Rainwater can be collected, filtered, and stored in a cistern or rainwater tank. It can then be used for a variety of purposes, including irrigation, washing cars, and flushing toilets, depending on the local regulations. Some homes and buildings have separate indoor plumbing for rainwater, while others may mix rainwater with city water for indoor use.