Construction dewatering

Dewatering is the process of removing groundwater which ensures construction work can occur safely, keeps water from seeping into the site which could affect engineering, and protects the ongoing integrity of the structure and surrounding area.

Groundwater is a complex and often very fragile resource which plays an important role in natural ecosystems and sub-surface hydrogeology. Also known as aquifers, groundwater sources can be accessed or interfered by different works such as basements, tanks, tunnels, trenches, and excavations.

If there is groundwater on a construction site, it needs to be removed before work can begin. The method required to dewater is determined by the geological conditions and characteristics of the soil, and the level, size and depth of excavation.

To undertake construction dewatering, the following approvals must be obtained from WaterNSW.

water supply work approval
water access licence (WAL) - unless the project qualifies for an exemption, please refer to the exemption aquifer interference activities taking 3ML or less and exemption for excavation dewatering taking greater than 3ML fact sheets for more information
water use approval - unless there is a development application from a local government authority.

If the construction project will involve dewatering, the integrated development assessment process can be initiated by the local council at the time of the development application (DA).

Emergency Dewatering

An exemption is now available under the Water Management General Regulation 2018 (Regulation) for use in emergencies. It applies to the removal of groundwater and overland flow water while undertaking urgent works in response to an emergency event. Visit the NRAR website for more information on Emergency works exemption.

What are the steps in the dewatering process?

Step 1: Submit the development application and supporting documents to council

Council submits all documents to WaterNSW via the NSW Planning Portal.
Review the requirements for a Geotechnical Investigation Report
WaterNSW completes an initial review and refers to the Department of Planning Industry and Environment (DPIE) for a hydrogeological assessment.
Council then notifies the applicant of the general terms of approval (GTAs).
Read Dewatering information for councils and applicants fact sheet for information about construction dewatering and which approvals may be required to authorise dewatering.

Step 2: Apply for necessary approvals

Submit the following applications as required, noting that exemptions (refer to the exemption aquifer interference activities taking 3ML or less and exemption for excavation dewatering taking greater than 3ML fact sheets) are in place for some approvals:
- record the page number of each item in the Geotechnical Investigation Report and include as a cover sheet
- water supply works approval for construction dewatering – check requirements to see if a dewatering management plan is needed
- water access licence (WAL) and source water if needed
- assign share components between water access licences
WaterNSW issues approval(s)/licences with conditions.
The Dewatering information for councils and applicants fact sheet provides information about which approvals may be required to authorise dewatering.

Step 3: Commence dewatering

Ensure metering is in place as per the dewatering management plan.
Track water take and maintain records using the record of groundwater take form for the completion report.
If approved water take likely to be exceeded, contact WaterNSW immediately.
Any suspected breaches of water law will be referred to the Natural Resources Access Regulator (NRAR)

Step 4: Complete dewatering or apply for an extension

Notify WaterNSW when dewatering is complete.
If dewatering is not completed in two years, an application is needed for an extension (12 months).
If planning to extend, an interim report is required in similar format to the completion report.
WaterNSW notifies applicants 60 & 30 days ahead of the expiry date.

Step 5: Submit completion report and surrender approvals

Call WaterNSW to lodge a request to surrender a water supply work approval before the expiry date of the original approval.
Ensure surrender is confirmed in the completion report.
On completion, prepare and submit completion report to WaterNSW.
WaterNSW certifies that the completion report satisfies all conditions.

Step 6: Complete construction