The Thames isn’t "clean" in the Instagram-filter, crystal-clear sense. It is alive, and that vitality comes with mess and complexity. You wouldn't ask a pub of 200 years whether its floors are perfectly clean; you’d celebrate that it still serves a good pint. The Thames is that pub.
So how clean is it? Clean enough to support life, art, and a steady stream of paddleboarders. Dirty enough to remind us that we are part of a city that is still figuring itself out. It’s a river that holds a mirror to London: gritty, resilient, and surprisingly beautiful when you let your guard down.
