Totally OT: Water tank weirdness

The problem started with the appearance of dust and grit falling into  
the bath. It was not at all obvious where it was coming from. With  
showers being preferred, the bath is little used, so this wasn't coming  
from the taps. I climbed into the roof space above the bathroom, but  
nothing was apparently amiss.

In the roof space there is an old tank, which I surmise was once the hot  
water tank. It has long been unused, and was presumably left there  
because it would be difficult to remove, and there was no compelling  
reason to do so. There is also some pipework that I had originally  
presumed was unused.

It's very dusty up there, and I have to wear a proper filter mask. As I  
was returning the mask to the garage area below the living area of the  
house, where I keep such things, I heard a noise coming from the hot  
water tank. Turned out there was a leak from where the heating element  
goes in. Given that the tank is under pressure, the leak was making a  
hissing noise.

Now, some years ago, I tried to trace the origin of the water-hammer  
noise, searching under the house without success.

My visit to the roof space made me wonder whether that pipe was really  
unused. Indeed it appears to have been sealed off. I now think that one  
part of it goes down the wall into the garage area to join the hot water  
output, with the other part heading down to the laundry. And where it  
goes down the wall is close to where the dust and grit is falling into  
the bath.

All of which makes me think that the dust and grit in the bath and the  
leak in the hot water tank are not unrelated. My theory is that this is  
the pipe that makes the water-hammer noise, given that it's not well  
attached to the framework, and that the tank leak changed the hammer  
pattern enough for the pipe to disturb different dust/grit in the roof  
space which is then able to enter the bathroom through a small gap in  
the ceiling trim.

On one level, this seems rather far-fetched. Yet the coincidence in  
timing is remarkable.

Sylvia.