For most Sydney properties, the best option is to connect each downpipe to a suitable stormwater system that drains to the property’s approved discharge point. The correct arrangement depends on council requirements, existing drainage, roof runoff and site conditions.
Comparing downpipe drainage options
| Option | When it may be suitable | Main limitation |
|---|---|---|
| Stormwater connection | Where a serviceable system can carry roof runoff to the approved discharge point. | The outlet, pipe condition and connection status must be confirmed; a nearby kerb, pit or pipe is not automatically available for connection. |
| Rainwater tank | Where roofwater will be stored for permitted reuse. | The tank needs an overflow that drains safely when full. It does not replace the property’s stormwater strategy. |
| Soakaway, soakwell or absorption trench | Where soil permeability, groundwater conditions and available space make infiltration suitable. | Clay, saturated ground or inadequate separation from buildings and boundaries may make infiltration unsuitable. Local approval requirements vary. |
| Controlled surface drainage | Where an approved area has sufficient fall and runoff will not cause ponding, erosion or impacts beyond the property. | It is unsuitable if water can affect buildings or flow onto neighbouring land. |
What determines the right option?
Confirm the property’s approved stormwater discharge arrangement first. The relevant council can advise what records, assessment or approval may be required.
Also consider:
- Existing drainage: Where the downpipes lead and whether buried pipes are correctly connected and serviceable.
- Roof runoff: Catchment area and design rainfall determine the required system capacity; this needs site-specific assessment.
- Site fall: Gravity drainage requires a workable route without harmful ponding.
- Ground conditions: Soil permeability, groundwater and available space determine whether infiltration is viable.
- Overflow: Tanks and infiltration systems need a safe route for excess runoff during heavy or prolonged rain.
You can observe visible downpipe routes and note ponding during rain. Do not excavate, connect or alter buried drainage yourself: underground utilities may be present, and the work may require council approval and an appropriately licensed plumbing or drainage contractor.
If the discharge point or buried pipe condition is unclear, contact our Sydney plumbing team for an assessment before changing the downpipes.