Recently took a tour of the newest water treatment plant on the Kelani River. I realized I talk about water a lot, but most people don’t really know the process. To put it simply, it is essentially just filtering and disinfecting. Most of the technology is well established (meaning old), but is quite effective. Here are the (very) general steps.
From here, the water is sent to more filters, chlorine disinfection and finally to a storage tank for piped delivery. I have no pictures of the filter since it was build underground at this particular plant. A plant like this would typically cost about $50 million to $100 million.