The topic of this project is exploring design directions towards a smart private-bathroom service/product. It is often the case that a bathroom is used by multiple people after each other. An unclean bathroom environment can hinder the user experience. The shared bathroom also involves a peak usage issue. These two points will cause dissatisfaction among users. So, the design goal is to (1) reduce user’s effort when cleaning the bathroom and (2) assist users in using the bathroom together by a technical solution. The final output is a smart toilet lid with three interaction concepts of different smart levels. Through evaluation and analysis, I found that users with high acceptance of smart products tend to choose smart products as an “assistant”; on the contrary, users with low acceptance of smart products tend to choose “tools”. For the former, they are more concerned about what personal data is collected and they expect a balance between personal data and smart services.