Isolate areas and if your pressure increases then you can concentrate in that area. Check for wet ground, also check in areas where some recent work has been done in the ground. Pipes under houses can break also, crawl spaces etc. You can use a leak detected also.
I think you mean “well” not “wall”. To find a leak in casing, run a temperature probe and log the well casing from top to bottom. ( well must be stabilized, not used for at least 48 hours ) Perform a fresh water injectivity of 5m3-10m3. Rerun temperature probe and log top to bottom. Send me the data and i’ll tell you exactly where your lek is in the casing. I’ll even tell you how to repair the leak.