Construction dewatering

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.

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 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?

  • 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.
  • 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.
  • Use the WaterNSW acceptance of the completion report to obtain an occupancy certificate.


Tuesday 17 May
2,573,926 ML
2,581,850 ML
9,342 ML
1,335 ML
50,768 ML
Tuesday 17 May