In this paper, the automatic water supply systemis presented. This paper suggests an IoT device for automatic plant watering when the soil moisture level drops below a threshold value. The proposed system can be implemented in various projects like green buildings, roof farming, etc. The IoT device is connected to the internet, enabling the user to receive moisture level updates. The paper aims to address the need for an efficient plant watering system by providing an automatic solution using IoT technology. This paper presents the design and development of an automatic water supply system using IoT technology. The system detects the soil moisture level of plants and automatically waters them when the moisture drops below a certain threshold value. The proposed system is suitable for use in green building projects and roof farming. The device is connected to the internet, allowing the user to receive real-time updates on moisture levels. The paper details the development process and the key components of the system, including sensors, actuators, and the microcontroller. The work done & presented in this paper is the result of the mini-project work that has been done by the first sem engineering students of the college and as such there is little novelty in it and the references are being taken from various sources from the internet, the paper is being written by the students to test their writing skills in the starting of their engineering career and also to test the presentation skills during their mini-project presentation. The work done & presented in this paper is the report of the assignment / alternate assessment tool as a part and parcel of the academic assignment of the first year subject on nanotechnology & IoT.