Thankyou both for your comments. Sydney Water have a sample easement on their website and it is titled “easement for sewage purposes over existing line of pipes” but of course it has to allow for maintenance and repair as outlined in the Conveyancing Act above. As we have had legal problems with our neighbours previously, I need to be specific in the wording. Currently I’m attempting to get the views of Sydney Water through a water-service coordinator, and if that fails, a second opinion from a solicitor or surveyor. Hopefully I can find someone who knows their business.