Ground saturation elevates risk of wastewater overflows in parts of central Auckland

JOINT STATEMENT, Watercare and Healthy Waters

We are aware of customers who have reported wastewater overflows on their properties around the Balmoral, Kingsland and Mt Eden area, where the underlying aquifer has filled to the point that it’s reached ground level in many areas.
Chief customer officer Amanda Singleton says: “During heavy rain, our wastewater network can get inundated with stormwater, causing it to overflow. The stormwater can get into the wastewater network a number of ways, including infiltration through small cracks in our pipes and inflow from flooded manholes.
“Given the unprecedented level of ground saturation in the area at the moment, the level of inflow and infiltration is far greater than normal – even though the rain has stopped, groundwater is continuing to enter our wastewater network. This is a situation we have not seen at this scale before.
“We really feel for our customers who have experienced overflows on their property – no one wants wastewater in their backyard. Our crews have been busy cleaning up private properties where our customers have reported overflows. If your property has been affected by an overflow, please avoid the area until we have been round to clean up.
“Until the ground dries up, we are likely to experience more overflows in this part of the network.”
Anyone who experiences a wastewater overflow at their property or sees one in a public area is urged to click here and report it.
Auckland Council head of Healthy Waters strategy Andrew Chin explains the Mt Eden aquifer is one of several natural springs that have reactivated in parts of Auckland, in some cases causing surface flooding and partial inundation of some buildings.
“This has happened because our groundwater levels are extremely high – one central Auckland monitoring site recorded its highest ever level, 2.5 metres higher than the typical winter peak.

“The flow from these springs is expected to slow over the coming days as the groundwater levels begin to fall.
“In the meantime, we’re asking Aucklanders to be careful around any new springs. They may erode material from underground, forming cavities that can collapse as sinkholes so please stay away from the spring, especially if you see there is silt in the water.”