Sand filter capping was tested as a new method for cleaning water in Mosul, Iraq. The researchers built a small plant to try different combinations of sand and anthracite coal to see which worked best. They found that using 20 cm of anthracite coal over 40 cm of sand was the most effective. This method not only improved water quality but also saved money by reducing the need for disinfectants and filter sand. The filters could run longer without needing to be cleaned, producing more clean water. Overall, the water produced met high standards and was good for health. Sand filter capping is a good option for cleaning water in different conditions.