You'll need to apply for a build over agreement if you're building: Within 3 metres of a public sewer or lateral drain. Within 1 metre of the point where a pipe serving only your property crosses your boundary (where it becomes a public lateral drain)

They can be as shallow as 12″ to 30,” or as deep as 6+ ft. Often times this is simply a matter of climate. In really cold climates, the pipe is buried deeper to prevent the pipe from freezing solid in winter. Every now and then you will run into a sewer line that is buried deep even in a warm climate.

A lateral drain is a length of pipe which carries wastewater away from your property to a sewer. It's usually located outside your property boundary, often under a public pavement or road. A lateral drain might run under your property if you share a sewer with your neighbour.

House Sewer: This the sewer system which is most commonly found in domestic houses where the plumbing system in a house is connected to the municipal sewers to carry out sanitary sewage. Lateral Sewers: These sewers carry sanitary sewages from more than one house sewer.