I don't want to sound like a jerk -- that is a mild lie. I am a total jerk. -- but where I live in Chelsea there are at least two spots that look like this on my way to work.
Okay, they aren't that bad, there are two distinct spots near South Kensington that spew hundreds of liters of water a day. I know the council is aware of the leaks, because they were considerate enough to grit all around them when it was cold.
Perhaps they are keeping this fresh running water available to the homeless population. That is a very kind thing of the RBKC. Or maybe they are trying to keep the levels of the Thames up by dumping water from the main right into the drains. In one of the cases, on Brompton road, the water comes right out of a mains access, runs about two meters down the gutter, then flows right into a drain. It has been going on now for about 3 months.
I wonder if I could get Boris to come down with a couple of buckets and save some of the water that is running down the drain. I hear he is a hands on type of guy... Boris? You out there? You want to come save some of this Chelsea Water?