And the Water Battle Continues

The almost undoubted main water problem is that wretched gap between the cast iron tank and the wall below.   Continual efforts to seal it are frustrated by the expansion and contraction of the iron tank which exceeds that of the stone, leading to cracks in the seal like this one:

I discovered a bitumen based sealant which can be painted into and over such cracks.  The clever bit is minute fibres suspended in the bitumen which add strength.   Not only that the job can be done from the very top rim of the tank using a six foot paintbrush of my design.  This means there is no need to scaffold the tower to enable safe access.  Should cracks recur the job can be done again.

Not only do the fibres give strength, they grip onto the inverted paintbrush avoiding drips.

And this is how that section looks after three coats of the reinforced bitumen seal.  Not pretty but it's invisible from all normal viewpoints.  Not bad considering it was done from the thin dry end of a six foot long paintbrush.  Just need some rain now.