Why does reverse osmosis cost so much?

One might wonder, why does the process of reverse osmosis cost so much? After all, it seems to be a relatively straightforward technique of pushing water through a semi-permeable membrane to achieve purification. However, the costs associated with reverse osmosis are not just limited to the equipment required. There are additional expenses such as energy consumption, maintenance of the system, and the need for periodic membrane replacement. Furthermore, the quality of the water source itself can significantly impact the efficiency of the process, often necessitating pre-treatment steps that further add to the overall cost. Given these various factors, it's understandable why reverse osmosis can be a costly investment for both residential and industrial water purification needs.