Tree roots can be aggressive and can often exert pressure on buildings, footpaths, fences and pipes. Existing cracks in pipes allow root invasion, as tree roots will seek out sources of moisture and nutrients.
Under the LocalGovernment Act 1993, councils 'by notice in writing served on the owner or occupier of land, may require the owner or occupier to cut the roots of a tree or bush or remove a tree or bush the roots of which are interfering with any building or structure on or under other land' (Part 12, Section 184).
Pouring herbicides down blocked drains will not clear the roots but will almost certainly result in pollution problems and will kill the tree. Find out where the drains and pipes are on your property before planting large trees. Many councils have information about trees to avoid near drains.
Plans of public and relevant private drains can be viewed by contacting Council's Engineering Department on 6382 8800.