To stop your neighbour’s water draining into your yard, document where it crosses the boundary, discuss the source with your neighbour and have redirected or concentrated flows corrected where possible. Before installing boundary drainage, obtain a professional assessment to ensure collected water has a suitable, lawful discharge point.
Identify the source
Observe the water during rain. Natural surface runoff generally follows the existing slope across a broad area. Redirected or concentrated water may emerge from a downpipe, pipe outlet, driveway, paving, retaining wall or recently altered landscaping.
Take dated photos or videos showing:
- where and when water crosses the boundary
- its direction and approximate spread or depth
- any feature concentrating the flow
- pooling, erosion or property damage
- recent building or landscaping changes.
This evidence will help your neighbour, council or drainage professional assess the issue without assuming legal responsibility. Do not enter the neighbouring property or excavate around concealed services.
If the water smells like sewage, contains waste or is near electrical equipment, keep people and pets away and avoid contact. Arrange urgent professional help; call emergency services if there is an immediate electrical danger.
Address the cause before installing drainage
Show your neighbour the evidence and ask whether the source can be corrected. A disconnected downpipe or changed ground level should be assessed at its source rather than automatically managed on your property. Confirm where downpipes should discharge before changing any connection.
If interception is necessary, a drainage professional should assess ground levels, soil, buildings, retaining walls and available discharge points. Site-dependent options include regrading, swales, grated channels, stormwater pits and subsurface drains. Existing plans and visible access points may help you find stormwater drains on your property without excavation.
A French drain is not suitable everywhere. Its effectiveness depends on soil, groundwater, nearby foundations or retaining walls, and a suitable outlet. Do not divert collected water onto another property, the street or any other location unless that discharge method is permitted.
Before digging, use Before You Dig Australia and check with relevant asset authorities to locate underground services. Leave excavation near utilities, footings or retaining walls to qualified contractors. Plumbing or drainage connections that constitute regulated work must be completed by an appropriately licensed contractor.
When to seek help
Contact your local Sydney council if the neighbour’s stormwater runoff appears connected to recent building, paving, retaining-wall, landscaping or drainage work that may require approval or compliance investigation. Council processes and enforcement powers vary, so ask what your council can investigate.
Arrange a drainage assessment when:
- the source or permitted discharge route is unclear
- water repeatedly pools against a building
- pipework, pits or drainage connections may be needed
- erosion or retaining-wall stability is a concern
- safe observation cannot establish the cause.
A licensed plumber or drainage specialist can assess levels, pipework and discharge options. Overland-flow, geotechnical or structural issues may require an engineer. If the correct solution remains unclear, contact our licensed Sydney stormwater plumbers before installing drainage.