In article ,
Chris J Dixon writes:
Andrew Gabriel wrote:
What makes you think a tree owner is in any way responsible
if his tree blocks a sewer? A tree root is not the slightest
bit interested in a sewer pipe, unless it's already broken.

So it couldn't possibly be the agent of damage, in the same way
that roots can lift pavements, damage walls etc?

I asked a drain surveyor that same question, and he said he'd
never seen a pipe run knocked out of true by even very thick
roots -- they just go round them like they were lumps of rock.
An exception is when a tree is losing anchorage in the ground
and roots may be moving in the wind. He had seen a couple of
cases where cameras showed pipework knocked out of true, and
in both cases, before they returned to reline the pipes, the
sewer had been completely ripped out when the tree fell.

What normally happens is a joint leaks, and the roots seach
out the source of moisture, entering and blocking the pipe.
However, the tree would never have known it was a pipe unless
it was already leaking.

--
Andrew Gabriel