Drainage Maintenance 

The City has over 4600 drainage pits and soak wells to manage stormwater throughout the City’s road network. As part of this drainage network, there is an additional 70 kilometres of underground pipes directing stormwater to 40 drainage basins or sub-surface detention and infiltration cells.  

The City engages a contractor to clean and inspect stormwater drainage pits and pipes throughout the City on an annual basis. This ensures the drainage network is clear and operates at full capacity.   

The City also conducts general maintenance on drainage infrastructure including the replacement of damaged pit lids and other infrastructure when damage occurs. When necessary, the City will upgrade drainage infrastructure at the same time to minimise costs and disruption, and continue to improve the overall capacity of the drainage network.

Stormwater Drainage FAQs

These Frequently Asked Questions address key aspects of stormwater infrastructure, including:

  • The difference between soak wells and drainage pits.
  • Understanding groundwater depth and the suitability of soak wells or drainage pits based on water table levels.
  • Property owner responsibilities for maintaining drainage systems to prevent flooding.
  • Emergency contacts during flood events.

Please download the Stormwater Drainage FAQs here (PDF, 111 KB).

What is the difference between a soak well and a drainage pit?

A soak well is a cylindrical concrete tank with angled holes in the side walls and a large hole in the base, allowing water to soak into the surrounding soil.

A drainage pit is a fully enclosed cylindrical concrete tank with no holes in the sides or base. It drains stormwater via a pipe network to a drainage sump.

What is the depth of groundwater beneath my property?

Groundwater depth varies seasonally and by location.

The Department of Water and Environmental Regulation provides general groundwater level data through the Perth Groundwater Map. However, this information may not reflect site-specific conditions.

For newer subdivisions, the City may have more detailed groundwater records. Builders and developers are encouraged, or may be required, to undertake further investigations.

Why is there a drainage easement within the lot boundary?

A drainage easement is required when public drainage infrastructure runs beneath private land.

Easements ensure that structures are not built over drainage lines, protecting the infrastructure and allowing access to maintenance. Easement details are listed on the property title, although not all properties with public infrastructure have registered easements.

Due to restricted space within a lot, can deeper soak wells or drainage pits be used?

Soak wells work best when the water table is well below their base, allowing water to infiltrate into sandy soil.

If the water table is high, then shallow soak wells with a larger diameter need to be used to provide adequate storage capacity.

Builders, developers and property owners must consider seasonal groundwater fluctuations and ensure there is enough space within the lot for installation and ongoing maintenance of soak wells or drainage pits.

How can a resident assist in avoiding flooding?

Residents can help reduce the impact of severe weather by ensuing all drainage infrastructure on their properties is adequately maintained.

  • Keep gutters and downpipes clean and in good working order.
  • Ensuring soak wells and drains are clean and free of debris.
  • Remove excessive material from entry pits and drainage grates, only if it is safe to do so.

Who can be contacted for help?

  • State Emergency Service: 132 500 – For flooding or storm damage on your property.
  • Western Power: 13 13 51 – For electrical emergencies.
  • ATCO Gas: 13 13 52 – For gas leaks or infrastructure damage.
  • Water Corporation: 13 13 75 – For wastewater or mains water issues.
  • City of Nedlands After Hours: 08 9273 3500 – For assistance outside business hours.

 

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