My strange hobby was going on what I called "leak walks".
I lived in a town where on any sunny day I could go for a walk and be almost guaranteed to spot a water mains leak I hadn't seen before, which I'd then report and see how long it would be before it was fixed.
The record was over a year for one of them.
( Yes, it was a Thames Water area. )
If it is a Thames Water area, you are lucky if the leak is only water...
There was one I thought was maybe a waste-water leak from the smell, but generally wastewater leaks are much harder to spot, and it's generally CSOs (Combined Sewer Overflows) that are the main problem there, which happen in heavy rainfall and not so much in residential areas.
Mains-water leaks however are easy to spot, because they're damp patches (or flowing/trickling water) in otherwise good weather.