A sand filter is a device used to remove impurities from water by passing it through a layer of sand. The sand traps particles, dirt, and other contaminants, allowing clean water to flow through. This method is commonly used in swimming pools, drinking water treatment, and wastewater management. Sand filters operate by gravity or pressure, depending on the system design. They require regular maintenance, including backwashing, to remove trapped debris and maintain efficiency. This simple yet effective filtration method is widely appreciated for its low cost and ease of use in various applications, including aquaculture and landscape irrigation.