How to find the sewer line on your property

Start at the gully trap

The gully trap is the open dish outside the house, usually below the level of the lowest fixture and near a kitchen or bathroom wall. It is the clearest above-ground marker of where the drainage leaves the building.

From there the lateral generally takes the shortest practical route to the boundary connection, though older properties often surprise you.

Look for inspection points and manhole lids

Inspection points - small capped risers set flush with the ground - are placed at junctions and changes of direction. Two of them give you a line. A manhole lid on or near the boundary usually marks the connection to the public main.

Pull the as-built from your property file

The drainage as-built lodged with the building consent is the record that shows the lateral's route across the section. Request the property file for your address from the council. See the drainage plans guide for how that request works.

Request the public network plan

The main itself belongs to the wastewater operator for your area. Find them in the directory below and request an extract for your address, or submit a locate request if you are excavating near the road corridor or an easement.

Trace it properly before you dig

Sewer laterals are shallow and often earthenware. Where the exact line matters - a new foundation, a pole, a pool - have the drain traced with a sonde or camera rather than working from the plan alone.