Household sewer drains carry wastewater from toilets, basins, sinks, showers and laundries through the property’s sanitary drainage towards its authorised wastewater connection or onsite system. Stormwater drains carry roofwater and surface runoff to an approved stormwater outlet, storage or infiltration system. The two systems must remain separate.
Colour, size, material and location are clues only, not proof. Trace visible stormwater connections and check what enters a pipe before drawing a conclusion.
Check the connection points
| Clue | Sewer | Stormwater |
|---|---|---|
| What enters it | Wastewater from sanitary fixtures | Rainwater or runoff from gutters, downpipes, pits and channels |
| Outdoor fitting | An overflow relief gully (ORG), which is a grated overflow point connected to the sanitary drain | A grated inlet, pit or channel that collects surface water |
| Where it leads | The property’s sanitary drain and authorised wastewater connection or onsite system | An approved stormwater outlet, collection or infiltration system |
An outdoor grate does not identify the system by itself. An ORG is part of the sewer drainage system, while a stormwater grate collects rainfall or runoff. Trace pipe connection points where they are safely visible rather than relying on appearance.
A downpipe should connect to the stormwater system, but concealed alterations or incorrect connections are possible. Do not assume a pipe’s purpose from its colour, diameter or material.
Confirm a concealed connection safely
Check any available Sydney Water sewer service diagram and relevant property or council drainage plans, but treat them as a guide. Availability and detail vary, and later alterations may not be recorded.
A licensed plumber can confirm the route using suitable methods such as CCTV inspection, electronic pipe locating or controlled dye testing. The appropriate method depends on the drainage layout and access.
Do not open or enter drainage points, dismantle pipework, or pour chemicals or dye into a drain. Sewer openings may expose you to contaminated wastewater or gases. Keep away from a damaged or overflowing sewer opening and leave concealed investigation or alterations to an appropriately licensed plumber.
If the connection remains uncertain, contact our Sydney plumbing team for a CCTV drain and pipe inspection before any work proceeds.