Trees growing in sewer easement

My sewer runs along neighbour's land parallel to fence.
It is a taswater easement.
Neighbour has planted trees on top of the easement.
These trees have grown fast and are Eucalyptus. These specific trees grow to 30 metres.
Who bears the cost of removing the trees and fixing the pipes when they start to invade the sewer pipes?
Is it the neighbour whose trees these are.
Is it me whose sewer it is
Is it taswater whose infrastructure it is.

 

It would be best to seek the guidelines from the authorities first.
Then, direct that advice to respected parties that planted the trees. That includes, who selected these particular trees.
It's fine to say generally - let's plant trees. But, are they the right tree for that location?

 

I suspect its a grey area. Not meant to v dont are different issues. You arent meant to plant within X metres (often 5) of a easement. I suspect the water authority may have the tree cut down and could leave it in the yard. I wouldnt want to be liable for damage to infrastructure by planting a eucalypt of all trees.

If you have a concern your sewer (not yours as in ownership) could become damaged you could ask the authority who may seek the property owner to remove the offending plant or they may do it for them and leave them with a mess in the yard. Reinstatement may the owners cost for doing something so foolish.