>I am sure readers will have heard of the ground water project at Victoria Station – and it has been a success. No questions – it works, and works well. The system currently draws most of its cool water from the Tyburn river, which slightly leaks into the circle line – and is drained into a sump. That cool water is used to cool systems in the station at Victoria and is very efficient in how it cools the air for minimal electrical effort in pumping water.

I think using the Thames would involve a lot of plumbing and pumping.